to what other offense's are doing. by speeding up the game, he isn't able to situationally substitute, which has always been his strength. now, teams are able to keep his guys on the field that shouldn't be there.
this is why he's always talking about up tempo offense. he wants it out of the game, to his benefit. take last year, when he made claims about it getting guys hurt. of course, it's not true, but who cares? the other vocal guy? bret bielma, a similar coach.