I'm actually reconsidering my original response to this factoring in Hensou's input below...

There is some element of what he said and information you provided where maybe USC was a Signature Win, not necessarily because of how good USC was/wasn't, but because we were the only defense that made Williams look that bad and have kinda become known for that.

I heard he still gets asked by people what happened in that game, so this may be one of those ones still haunting him when he's 70.