Opinion for the Court filed by Circuit Judge SILBERMAN.
Opinion concurring in part and dissenting in part filed by Circuit Judge WALD, with whom Chief Judge EDWARDS and Circuit Judge ROGERS and Circuit Judge TATEL join.
[1261]*1261Opinion concurring in part and dissenting in part filed by Circuit Judge HENDERSON, with whom Circuit Judge SENTELLE and Circuit Judge RANDOLPH join.
SILBERMAN, Circuit Judge:
Diamond Walnut Growers, Inc. petitions for review of a National Labor Relations Board order holding that it committed an unfair labor practice in its placement of three returning strikers. We grant the petition for review in part and in part grant the NLRB’s cross-application for enforcement.
I.
Diamond Walnut processes and packages walnuts for national and international distribution. The company operates with a year-round workforce, supplemented by additional seasonal hires during the fall harvesting season. Diamond’s employees have for years been represented by Cannery Workers, Processors, Warehousemen and Helpers Local 601 of the International Brotherhood of Teamsters, AFL-CIO (the union). In September of 1991, following expiration of the most recent collective bargaining agreement between Diamond and the union, nearly 500 of Diamond’s permanent and seasonal employees went on strike. Diamond hired replacement workers to allow it to continue operations.
By all accounts, the strike was, and remains, a bitter affair. The strikers are alleged to have engaged in various acts of violence against the replacement workers, especially at the outset of the strike, and restraining orders issued against both strikers and replacements. See generally Diamond Walnut Growers, Inc., 312 N.L.R.B. 61, 1993 WL 356124 (1993). In addition, as part of its effort to exert economic pressure on Diamond, the union undertook an international boycott of its product. The boycott included a well-publicized national bus tour during which union members distributed to the public leaflets which described Diamond’s workforce as composed of “scabs” who packaged walnuts contaminated with “mold, dirt, oil, worms and debris.”
Approximately one year into the strike, the Board held a representation election. The union lost the election, but its objections prompted the Board to order a rerun to be held in October of 1993. Just over two weeks prior to the new election, a group of four striking employees, represented by a union official, approached Diamond with an unconditional offer to return to work. According to the letter presented to the company at that time by their representative, the employees were convinced that “a fair election [was] simply impossible.” Nonetheless, the employees “fe[lt] that it [was] important that the replacement workers ... have an opportunity to hear from Union sympathizers.” Thus, the group of strikers was “available and willing to return to immediate active employment.” The following day, the union notified Diamond that pursuant to the above-quoted letter, two additional strikers were willing to return to work.
It is undisputed that for three of the returning strikers, neither the permanent jobs they held before the strike, nor substantially equivalent ones, were available at the time of their return. Diamond placed these three in various seasonal jobs, and it is these placements which led to the order under review. Prior to the strike, Willa Miller was a quality control supervisor; she was placed in a seasonal packing position even though a seasonal inspection job was available. Alfonsina Munoz had been employed as a lift truck operator and, despite the availability of a seasonal forklift job, was given a seasonal job cracking and inspecting nuts in the growers’ inspection department at the front end of the production process. Mohammed Kussair, formerly an air separator machine operator, was, like Munoz, placed in a seasonal cracking and inspecting position in the growers’ inspection department. Neither Miller nor Munoz complained to Diamond about their job placements. Kussair asked to be transferred to a loader position for which he was qualified after receiving three oral reprimands for failing to meet his daily quota, the third of which led to a written reprimand. Diamond sought to accommodate Kussair’s transfer request, but he left to rejoin the strike before it could do so.
The rerun election took place as scheduled, and the union lost. Following that election, the General Counsel filed a complaint alleg[1262]*1262ing that Diamond had violated sections 8(a)(8) and 8(a)(1) of the National Labor Relations Act, 29 U.S.C. §§ 158(a)(3), (a)(1) (1994),1 by unlawfully discriminating against Miller, Munoz, and Kussair. The General Counsel alleged that because of their protected activity, Diamond declined to put them in certain available seasonal positions for which they were qualified and that were preferable to the positions in which they were actually placed. After a hearing, an administrative law judge recommended that the charges be dismissed. He found that Diamond had “discriminated” insofar as it had placed the employees at least in part because of their protected activity, but he did not think that discrimination “unlawful” under the Board’s decision in Rose Printing Co., 304 N.L.R.B. 1076, 1991 WL 197152 (1991), which held that an employer’s “obligation to reinstate former economic strikers extends only to vacancies created by the departure of replacements from the strikers’ former jobs and to vacancies in substantially equivalent jobs.” Id. at 1076. The ALJ also recommended that if the Board should reverse him and find that Diamond did discriminate against the returning strikers within the meaning of the Act, it should conclude that it committed an unfair labor practice, since Diamond “faded to establish legitimate and substantial business justifications for placing the returning strikers in the jobs to which they were assigned.”
The Board reversed. It thought the ALJ had overlooked the statement in Rose Printing to the effect that returning strikers who had no right to reinstatement (because of the unavailability of their former jobs or substantially equivalent ones) were nevertheless “entitled to nondiscriminatory treatment in their applications for other jobs.” Rose Printing, 304 N.L.R.B. at 1078. As the Board put it, “although [Diamond] was under no legal obligation ... to reinstate the strikers ..., once it voluntarily decided to reinstate them, it was required to act in a nondiscriminatory fashion toward the strikers,” Diamond had discriminated against Miller, Munoz, and Kussair, in the Board’s view, by declining “to place them in the [seasonal] positions of quality control assistant, lift truck operator, and loader, respectively, because of their union status and/or because of certain protected union activity they engaged in while on strike.” Employing the burden-shifting framework spelled out by the Supreme Court in NLRB v. Great Dane Trailers, Inc., 388 U.S. 26, 87 S.Ct. 1792, 18 L.Ed.2d 1027 (1967), and NLRB v. Fleetwood Trailer Co., Inc., 389 U.S. 375, 88 S.Ct. 543, 19 L.Ed.2d 614 (1967), the Board then examined Diamond’s asserted justifications for placing the three returning strikers as it did. The Board rejected the contention that the placements were warranted by the employer’s concern that the replacement workers might instigate violence against the three and thus justified placement in well-supervised jobs, since “there [was] no evidence that Miller, Munoz, or Kussair were involved” in the strike-related violence allegedly causing Diamond’s concern. The Board also dismissed the notion that the placements of Miller and Munoz were justified by their participation in the boycott and the circulation of disparaging leaflets: “[T]he strikers’ conduct constituted protected ... activity and there is no evidence indicating that such protection was lost because of threats made by Miller and Munoz to damage or sabotage [Diamond’s] equipment or products.” Since Diamond had failed to justify its discrimination, the Board found unfair labor practices, the severity of which, “in light of ... their timing,” warranted setting aside the rerun election.
A divided panel of this court granted Diamond’s petition for review and denied the Board’s cross-application for enforcement. Diamond Walnut Growers, Inc. v. NLRB, 80 F.3d 485 (D.C.Cir.1996). The full court then [1263]*1263vacated the panel’s judgment and ordered that the case be reheard en banc.
II.
Diamond Walnut challenges the Board’s determination that it lacked substantial business justification for refusing to place the three employees in the specific jobs they sought — quality control assistant, lift truck operator, and loader. It is undisputed that the Fleetwood framework governs this case. The General Counsel under Fleetwood must make out a prima facie case that the employer discriminated within the meaning of the Act, which means the employer’s decision as to how to treat the three returning strikers was attributable to their protected activity. Rose Printing establishes that a struck employer faced with an unconditional offer to return to work is obliged to treat the returning employee like any other applicant for work (unless the employee’s former job or its substantial equivalent is available, in which case the employee is preferred to any other applicant). See 304 N.L.R.B. at 1078. But Miller and Munoz were not treated like any other applicant for work.2 Miller was qualified for a seasonal position in quality control that paid 32 cents per hour more than the packing job to which she was assigned. And Munoz was qualified to fill a forklift operating job, a position that paid between $2.75 and $5.00 per hour more than the walnut cracking and inspecting job she received. Diamond admits that it took into account Miller’s and Munoz’s protected activity in choosing to place them in jobs that were objectively less desirable than those for which they were qualified. Petitioner, although it contended that the discrimination was comparatively slight, does not dispute that its action discriminated against Munoz and Miller within the meaning of the Act. See Great Dane, 388 U.S. at 32, 87 S.Ct. at 1796-97; Laidlaw Waste Systems, 313 N.L.R.B. 680, 1994 WL 57456 (1994).
Judge Henderson, nevertheless, devotes much of her opinion, Op. at 1-8, to a proposition not argued by petitioner before the Board or this court: that even if Diamond Walnut’s placement of Miller and Munoz was discrimination, it was not a violation of § 8(a)(3) because it was not discrimination that “discourag[ed] membership in any labor organization.”3 It was just too insignificant to influence other employees, therefore the General Counsel never even made out a prima facie case. As we discuss infra, however, it is well-established that a party may not raise before us an argument not presented to the Board, see Sheet Metal Workers, Local Union No. 91 v. NLRB, 905 F.2d 417, 422 n. 10 (D.C.Cir.1990), and equally well-established that we do not consider arguments not presented to us. See Corson & Gruman Co. v. NLRB, 899 F.2d 47, 50 n. 4 (D.C.Cir.1990). Judge Henderson explains her diversion from petitioner’s case by relying on petitioner’s broad statement of the issue presented (before the panel): “whether the NLRB properly found that Diamond ... violated § 8(a)(3) and § 8(a)(1) of the Act.” Judge Henderson’s Op. at 1-2, n.l (emphasis added). Under that reasoning — which we do not accept — we would be equally free to consider any legal issue implicit in that finding, such as whether the statute of limitations on the General Counsel’s complaint had expired or, for that matter, whether the General Counsel was an imposter.
Under Fleetwood, after discrimination is shown, the burden shifts to the employer to [1264]*1264establish that its treatment of the employees has a legitimate and substantial business justification. See 389 U.S. at 378, 88 S.Ct. at 545-46. Petitioner declined to give Munoz the forklift driver job because of its concern that driving that piece of equipment throughout the plant would be unduly risky in two respects. First, because of the bad feeling between strikers and replacements, Munoz would be endangered if confronted by hostile replacement workers in an isolated area. Second, since Munoz had participated in the bus tour during which the union had accused the company of producing tainted walnuts, Munoz would be tempted to engage in sabotage by using the 11,000 pound vehicle to cause unspecified damage. As for Miller, who was also on the bus tour, the company declined to put her in the “sensitive position of quality control assistant” where “the final visual inspection of walnuts is made prior to leaving the plant.” In that position, she would have “an easy opportunity to let defective nuts go by undetected ... or to place a foreign object into the final product, thereby legitimizing the Union’s claim of tainted walnuts.” 4
The Board rejected as insubstantial the employer’s reasons for assigning both employees. We discuss the two situations separately below, but before doing so we deal with a generic argument petitioner raises. It is claimed that the Board’s entire approach in this case is inconsistent with its recent opinion in Sunland Construction Co., Inc., 309 N.L.R.B. 1224, 1992 WL 390105 (1992). In Sunland, the Board considered the claim to reinstatement of a striking employee who was a paid union organizer. The Board concluded that the employer had a legitimate and substantial justification to deny reinstatement because of concerns over the union “agent’s” possible conflict of interest. See id. at 1231. Here, the ALJ assumed, and the Board accepted, that the three returning strikers were “agents” (though not paid) of the union. Diamond argues that the Sun-land right to deny reinstatement to paid union agents necessarily includes the lesser right to place restrictions on the jobs for which such agents will be considered, and it further contends that the fact that the employees in this case were not paid should make no difference. Insofar as Diamond argues that Sunland is inconsistent with the order under review, or at least should have been reconciled, it is an argument that should have been made to the Board. The ALJ determined that Diamond had not shown legitimate and substantial justifications for its treatment of the returning strikers, and, although he cited Sunland, he did so for the proposition that “the Board has continued to adhere to its view that there is no conflict of interest if an employee of the union seeks employment with a company to organize employees.” (Emphasis added.) Although Diamond prevailed on an alternate theory before the ALJ, it naturally filed exceptions to this determination (called a finding). The posture of the case was such that if Diamond thought that under Sunland the existence of an agency relationship, whether paid or not, justified its treatment of the returning strikers, it should have argued as much in its appeal from the ALJ’s decision. It did not. Our review of Diamond’s brief in support of its exceptions to the ALJ’s decision, as well as its opposition to the General Counsel’s and union’s exceptions, reveals that the company never cited Sunland to the Board, nor did it claim that the principles of Sunland should govern the case. We cannot fault the Board for failing to distinguish arguably applicable precedent when the petitioner never raised it or the proposition it stands for. See 29 U.S.C. § 160(e); Sheet Metal Workers, 905 F.2d at 422 n. 10.
A. Munoz
The Board rejected petitioner’s proffered justifications for its placement of Munoz on [1265]*1265the same grounds as did the ALJ. As to Diamond’s purported fear for her safety, no evidence had been produced that Munoz was thought to be responsible for any violence, so there was no reason to believe she would have been a special target. The Board said, “[T]here is no specific evidence that any replacements harbored hostility toward these three strikers, and, if such evidence did exist as [Diamond] claims, we fail to see how placing them in the positions to which they were assigned would lessen the perceived danger of retaliatory acts being committed against them.” The Board discounted Diamond Walnut’s contention that Munoz would be under greater protection if closely supervised, noting that petitioner had admitted that “Munoz freely roamed the plant unsupervised during her breaks.” The Board did not dismiss out of hand, however, the proposition that concern for a returning striker’s safety could ever amount to a substantial business justification for a “discriminating’’ placement; it was careful to state “we find that [Diamond] was not justified in restricting the strikers’ job placements out of fear that the replacement employees would retaliate against these three strikers.” By so reasoning, the Board implicitly rejected the view urged by Judge Wald5 — which is inconsistent with Fleet-wood — that an employer is never (or at least “hardly ever,” see Op. at 1271, n.2) entitled to treat returning strikers “diseriminatorily” (even with a substantial business justification) based on protected activity. See also NLRB v. Mackay Radio & Tel. Co., 304 U.S. 333, 58 S.Ct. 904, 82 L.Ed. 1381 (1938). The Board’s reasoning also necessarily suggests that it does not consider the substantial justification test as coextensive with the test for employee misconduct because whether the returning strikers were threatened with violence does not turn on their culpability.
As for the possibility that Munoz would engage in forklift sabotage, the Board was more terse, stating only that “the strikers’ conduct [referring to the bus tour] constituted protected ... activity,” and there was no evidence indicating that such protection was lost because of threats made by Miller and Munoz. If Munoz had uttered specific threats of sabotage, however, she would have lost her protected status and we would not be dealing with a Fleetwood situation at all; the General Counsel would not even have established a prima facie case. See, e.g., NLRB v. W.C. McQuaide, Inc., 552 F.2d 519, 528 (3d Cir.1977). It is true, as Judge Wald emphasizes, Op. at 1271-1272, that the Board has always insisted on specific evidence of striker misconduct before concluding that a striker has lost the protection of the Act. See, e.g., Medite of New Mexico, Inc. v. NLRB, 72 F.3d 780, 790 (10th Cir.1995). But that doctrine is not relevant to this case; petitioner, as we have noted, is not claiming that Munoz and Miller were guilty of misconduct. And the Board has not overlapped these two distinct concepts in the manner in which Judge Wald advocates — her newly designated specific evidence “rule.” Compare, e.g., Medite of New Mexico, 314 N.L.R.B. 1145, 1994 WL 508144 (1994) (examining whether an employee lost protection of the Act due to specific evidence of strike misconduct), enf'd, 72 F.3d 780 (10th Cir.1995); Calliope Designs, Inc., 297 N.L.R.B. 510, 1989 WL 224492 (1989) (same), with, e.g., Simland, supra.6 After all, the Fleetwood substantial justification test assumes that the employees in question have engaged in protected activity. See also General Electric Co. v. NLRB, 400 F.2d 713 (5th Cir.1968), cert. denied, 394 U.S. 904, 89 S.Ct. 1012, 22 L.Ed.2d 216 (1969). So we take the Board necessarily to have concluded that the possibility of Munoz engaging in future sabotage by misuse of her forklift was simply not a sufficient risk to constitute a substantial business justification for her treatment.
[1266]*1266Petitioner claims that the Board’s conclusion lacks “substantial evidence,” implicitly-assuming that that conclusion is a finding of fact. But it is apparent that the Board, in determining whether Diamond Walnut had a substantial business justification, was not really finding a fact; its determination was certainly not an appraisal of an historical happening. Instead, the Board made a normative judgment, a mixed poliey/legal determination, which would typically be reviewed according to the arbitrary and capricious standard of the Administrative Procedure Act (reasonableness). The NLRA’s judicial review provision, 29 U.S.C. §§ 160(e), (f), does not explicitly include the APA’s arbitrary and capricious standard, but the Supreme Court has always assumed that Congress intended the judicial review provisions' of both acts to be equivalent, see Universal Camera v. NLRB, 340 U.S. 474, 487, 71 S.Ct. 456, 463-64, 95 L.Ed. 456 (1951), and has read the NLRA as if it included an arbitrary and capricious test, see, e.g., Linden Lumber Division, Summer & Co. v. NLRB, 419 U.S. 301, 309-10, 95 S.Ct. 429, 434-35, 42 L.Ed.2d 465 (1974), as have we, see, e.g., Gilbert v. NLRB, 56 F.3d 1438, 1445 (D.C.Cir.1995); Cleveland Constr., Inc. v. NLRB, 44 F.3d 1010 (D.C.Cir.1995); cf. Bangor Hydro-Electric Co. v. FERC, 78 F.3d 659, 663 (D.C.Cir. 1996).7
An employer’s concern for the safety of a few returning strikers, put in the midst of a majority of replacements in a strike marked by violence, may be genuine, but it is hardly unreasonable for the Board to insist, at minimum, on evidence of a concrete threat to those strikers. Otherwise, such a generalized concern could all too easily serve as a handy pretext for disfavoring returning strikers. Moreover, if there were such a threat, the employer might well be obliged to take adequate prophylactic measures that bear upon those who threatened the violence rather than those who were threatened. Cf. Brown v. Louisiana, 383 U.S. 131, 133 n. 1, 86 S.Ct. 719, 719 n. 1, 15 L.Ed.2d 637 (1966) (rejecting the notion of a “heckler’s veto” in the First Amendment context). In sum, we think the Board’s conclusion on this point easily passes the reasonableness test.
Similarly, the Board was reasonable in its determination that the risk of Munoz engaging in sabotage while riding around on her 11,000 pound forklift — the petitioner seems to most fear her crashing the forklift into machinery — is not a substantial business justification for her disadvantageous placement in another job. Strikes tend to be hard struggles, and although this one may have been more bitter than most, there is always a potential danger of returning strikers, particularly while the strike is still ongoing, engaging in some form of sabotage. There is therefore undeniably some risk in employing returning strikers during a strike. But it could not be seriously argued that an employer cannot be forced to assume any risk of sabotage, because that would be equivalent to holding that an employer need not take back strikers during an ongoing strike at all — at least unless they manifested a break with the union. See Fleetwood, 389 U.S. at 380, 88 S.Ct. at 546-47. As the Supreme Court noted in NLRB v. Town & Country Electric, Inc., — U.S.-, 116 S.Ct. 450, 133 L.Ed.2d 371 (1995), the Board must consider “alternative remedies” available to a company that contends that rehiring union organizers would pose a risk of “unlawful (or possibly unlawful) activity.” Id. at-, 116 S.Ct. at 457. One factor to consider in evaluating the risk posed by a returning striker is the company’s ability to detect his or her unlawful activity. In this regard, if Munoz engaged in forklift sabotage, it would presumably be readily detectable.
Nevertheless, different Boards at different times might reach different appraisals as to how much of a risk of sabotage constitutes a substantial business justification. Compare Sunland, supra. It is important to recognize that where the Board draws the line has significant policy implications and the Board, as the Supreme Court has observed, is the agency Congress entrusted to formulate national labor policy. See, e.g., Curtin Mathe[1267]*1267son, 494 U.S. at 786, 110 S.Ct. at 1549. We therefore cannot quarrel with the Board’s decision that the potential sabotage risk of giving Munoz the forklift driver job was not a substantial business justification. Petitioner has shown no particularized evidence to buttress its primary concern — that there is a risk that she would misuse the forklift — and therefore the Board’s appraisal of the employer’s justification as inadequate, keeping in mind the labor policy implications, is not unreasonable.
B. Miller
The Miller case is another matter. It will be recalled that petitioner declined to assign her to the post of quality control assistant, the job responsible for the final inspection of walnuts leaving the plant (she received a job paying 32 cents an hour less). The Board rejected the employer’s justification, which was based on Miller’s participation in the product boycott and bus tour leafleting, saying only — as we have noted with regard to Munoz — “the strikers’ conduct constituted protected ... activity and there is no evidence indicating that such protection was lost because of threats made by Miller and Munoz to damage or sabotage ... equipment or products.” With respect to Miller, we think the Board’s determination that petitioner’s business justification is insubstantial is flatly unreasonable.
All strikes, as we have recognized, are a form of economic warfare, but when a union claims that a food product produced by a struck company is actually tainted it can be thought to be using the strike equivalent of a nuclear bomb; the unpleasant effects will long survive the battle. See Craig Becker, “Better Than a Strike”: Protecting New Forms of Collective Work Stoppages under the National Labor Relations Act, 61 U. Chi. L. Rev. 351, 375 & n.113 (1994). The company’s ability to sell the product, even if the strike is subsequently settled, could well be destroyed. If a customer becomes apprehensive to bite into Diamond’s walnuts because of a concern at finding an impurity (even part of a worm), it is unlikely that a strike settlement will eliminate that visceral fear. Petitioner does not challenge the Board’s conclusion that the “tainted walnuts” campaign was protected,8 and it is not up to us, sua sponte, to decide that issue. Compare Judge Wald’s Op. at 1278-1279; Judge Henderson’s Op. at 1284.9 But to conclude the campaign was protected obviously does not determine whether the company’s justification was substantial. The Fleetwood paradigm, we repeat, assumes protected conduct, as well as discrimination because of the protected conduct, before the burden shifts to the employer to produce a legitimate and substantial business justification. In that respect, not all protected conduct can possibly be thought equal; different protected conduct may well give rise to different justifications.
We therefore take the Board to mean, as we did regarding Munoz, that petitioner was [1268]*1268obliged to show something more than it presented to support its concern that putting Miller in the quality control position would provide her “with an easy opportunity to let defective nuts go by undetected or to place a foreign object into the final product thereby legitimizing the Union’s claim of tainted walnuts.” (Emphasis added.) Again, we emphasize that if petitioner had actual evidence that Miller had sabotaged the walnuts, which Judge Wald insists be produced, Op. at 1271-1272, Miller would be unprotected by the Act, and petitioner need not offer any justification for discriminating against her. The issue, then, is not whether there is sufficient evidence for the Board to have determined that Miller did not engage in past misconduct, but rather whether the employer had a legitimate concern, based on the undisputed evidence and the employer’s claimed factual inferences — presented to and unchallenged by the Board — that her' employment as a quality control assistant would have posed an unusual and serious risk that she would engage in future misconduct of a particular kind, at great cost to petitioner. Cf. Steffan v. Perry, 41 F.3d 677, 690 (D.C.Cir.1994) (en banc) (explaining circumstances in which the Defense Department can avoid the risk of future misconduct without a showing of past misconduct). The Board seems to have ignored those concerns without discussion, holding in effect (but not explicitly) that no matter what the objective risk to the employer of a returning striker’s possible mischief the employer can never meet the substantial justification test.
The Board does not quarrel with petitioner’s contention that the potential damage if the public learned of impurities in Diamond’s walnuts would be extraordinary. One well-publicized worm might eviscerate the company’s market share, especially in light of the public’s “awareness” (due to the union’s campaign) that Diamond’s product might be tainted. Nor does the Board dispute that Miller in the quality control position would have had the capacity to cause such damage to the company. Judge Wald offers an explanation for rejecting Diamond Walnut’s concerns not adopted by the Board, which relies on disputable interpretations of portions of the transcript (not even designated by the Board’s counsel as part of our record 10 presumably because the Board did not base any findings on that testimony), i.e., that the quality control assistant role is really not so important. It is simply not so, as Judge Wald asserts, Op. at 1273, that Diamond Walnut’s quality control manager testified that its “final product” “inevitably ha[s] defects such as mold, rancidity, and worms” (emphasis , added) (that sounds like the product boycott propaganda). In fact, he testified that the quality control assistant’s job is to alert the production people concerning defects in the production line and then it is up to the production people to “eliminate[] those defects from the product.”11
The Board’s counsel argues, as the Board implicitly concluded, that it is unfair to assume that an employee would behave in a disloyal and improper fashion. It is unnecessary, however, for us to make that assumption to decide the Board was unreasonable. The Board accepted petitioner’s contention that Miller would have been placed “in the sensitive position ... where final visual inspection of walnuts is made prior to leaving the plant,” which for purposes of judicial review is equivalent to the Board making a finding to that effect.12 Miller would therefore have been put in a rather acute and unusual conflict of interest in which her job for her employer could be thought to have as [1269]*1269a function the rebutting of her union’s claim. A similar conflict would be raised if she wished a bargaining unit job in the company’s public relations department. This conflict makes all too likely the possibility that Miller would be at least inattentive to her product quality duties, and inattention is all it would take for Diamond to suffer a potentially crippling blow. To make matters worse, any “mistake” by Miller on the product quality control line would not be easily attributable to her unless petitioner paid someone to stand all day looking over Miller’s shoulder — which obviously exceeds any reasonable requirement. If Munoz ran her forklift into valuable machinery, she would run a risk of being discovered and would therefore be deterred. But Miller, as a quality control assistant, could simply avert her eye and cause the damage with apparently little risk of discovery. Unlike the typical situation in which, as Town & Country recognized, see — U.S. at-, 116 S.Ct. at 457, an employer has other remedies to deal with sabotage, those remedies are clearly not adequate here. There is no remedy that might lie against Miller that could compensate Diamond for the type of damage even a moment’s lapse on her part could cause. In short, she would have had a special motive, a unique opportunity and little risk of detection to cause severe harm. Both the risk Diamond faced in its placement of Miller was qualitatively different than a normal risk of sabotage, and the deterrence to Miller’s possible misbehavior was peculiarly inadequate.
Our two groups of concurring and dissenting colleagues — from opposite vantage points — object to the distinction we draw between the Board’s view of the employer’s justification for its treatment of Munoz on the one hand and Miller on the other. To be sure, the Board, as we noted, was rather cryptic and categorical in rejecting petitioner’s claim regarding Munoz’s potential for sabotage, but we think that is permissible because petitioner did not present the Board with facts that would significantly distinguish the risk of placing Munoz in the forklift job from the risk an employer runs reemploying any returning striker. An agency cannot be expected to respond in a nuanced manner to a simplistic argument. See City of Vernon v. FERC, 845 F.2d 1042, 1047 (D.C.Cir.1988) (“[T]he Commission cannot be asked to make silk purse responses to sow’s ear arguments.”).
Petitioner did, however, present a powerful argument that placing Miller in the position of quality control assistant presented extraordinary risks and here the Board’s categorical rejection — in light of petitioner’s more focused claim — is unacceptable. Our colleagues accuse us of forcing the Board in the future to “draw fine lines” between those cases in which an employer’s discriminatory placement of returning strikers has a substantial justification and those that do not. Exactly so. That is the Board’s job; that is what Fleetwood calls for. Essentially the Board has to take into account in a case such as this some consideration of the risk the employer seeks to avoid. Judge Wald challenges us to lay down broader guidelines as to what sorts of jobs, in what sorts of companies, during what sorts of strikes, might be thought equivalent to Miller’s placement quality control position. But that is not the test of principled judicial decisionmaking. There may well be other situations in which an employer could produce compelling grounds for a relatively unfavorable assignment of a returning striker. The Board itself implied that a serious threat of violence against the striker might suffice. The legal proposition that governs this case, however, is that the Board must consider whatever special circumstances are presented by an employer asserting the defense of substantial justification, and it may not summarily reject an employer’s specific and persuasive explanation.
Our disagreement with our colleagues turns very much on our view of the “proper — and properly limited — role”13 of a court of appeals reviewing an agency decision. We must take a case respecting the boundaries of the controversy, boundaries set by the agency’s actual decision and petitioner’s particular challenges to that decision. [1270]*1270We simply are not at liberty to reconstruct the transcript before the ALJ to arrive at factual findings that the Board itself did not make. Nor are we free to base our decision on arguments that could have been presented to the Board — but were not; nor on legal reasoning the Board might have adopted— but did not.
We must, of course, give genuine deference to the Board’s interpretation and application of the Act, as glossed by governing Supreme Court decisions, as well as the Board’s factual findings and those legal/policy decisions implicit in the inferences drawn from those findings. But we are still obliged to ask in the last analysis whether the Board’s decision, as to whether the employer’s action was substantially justified by business reasons, falls within the broad stretch of reasonableness.14 In this case, at least with respect to one part of the Board’s decision, we conclude the Board exceeded the reasonableness limits.
So ordered.