Rose Bowl vs. Recruiting

OK, it’s been almost three months, but here’s a lingering question from the Rose Bowl.
USC’s undoubtedly compiled the nation’s top recruiting classes the past four years (or at least top three) but if that’s the case, it’s interesting to consider who was on the field on some of the most important plays of the game.
Perhaps the most memorable offensive play was Reggie Bushs lateral to a walk-on (wide receiver Brad Walker). Apparently Chris McFoy, Steve Smith, Dwayne Jarrett and Patrick Turner were not enough?
During Texas’ game-winning drive, USC’s defense featured twin brothers Ryan and Brandon Ting in the secondary. None of this is a slight of those players, who consistently work as hard (or harder) than anyone in practice.
But it shows that even with all those No. 1 classes, where were the so-called blue-chip players during those critical moments? Were they simply not utilized, hurt or just beaten out by their lesser-known teammates?

P.S. Does anyone remember Texas using walk-ons on any critical plays?