In Darr v. NLRB, 801 F.2d 1404 (D.C.Cir.1986), the Court vacated an order in which the Board had given deference to an arbitration award that was seemingly inconsistent with Board precedent. Id. at 1407-09. The Court reached this result primarily because the Board had failed to provide a coherent theory supporting its decision to give deference. The Court noted that the Board's decision might have been justifiable under the contractual waiver doctrine approved by this court in American Freight; but because the Board had failed clearly to espouse that, or any other, theory of deference, we remanded the case for further consideration. See Darr, 801 F.2d at 1408-09.