The more serious answer: I don't think that Williams has the experience level needed to do more than slow down a guy like Wilcox, he may have the athleticism and the size, but he needs to learn all the tricks that veterans will pull on him. Had Muss been giving him spare minutes here and there over the last several games, it wouldn't have been so much of a problem... but he didn't.
Corliss in no way resembles a center, but Muss knew that he could count on him for some numbers, even if they wouldn't be enough to save the game.
I agree that it was a mistake, but Muss had already painted himself into a corner by denying Justin minutes earlier on, so we had no obviously great options available.