The bottom line is, it doesn't matter that its "his third game back", I mean, if that is the case and he cannot handle the pressure being put on him, then maybe he DOES need to sit for a while..playing for ND and starting on the defense is a priviledge, not a right...he has to earn the spot, and thus far this season, he has been our achilles heel - lest we not forget that he broke to the inside instead of staying with that Michigan receiver who caught the winning pass against us two weeks ago....offenses are going to keep throwing to his side of the field ALL DAY...and given Tenuta's blitz-happy schemes, our corners are left on islands all day long - if Walls can't handle being out their on an island, he needs to let someone else have a shot.
He's young, yes, and I hope he continues to develop and improve - but every game is TOO big for him to have the luxury of developing during real-game situations - that is what practice is for.