Thus, some of his act wearing on kids is solved by the fact they leave before he reaches a breaking point with them. Rinse, wash, repeat.
I suspect they could/would win a NC under him before he leaves. He is that good IMO. He will light a fire under them every bit as bright as the fire Holtz lit under ND his first few years. We will see some drop in recruiting because he will get virtually any player he wants the first three years. Not fatal for us, but not good.
Worst of all, he will make Michigan better than ND for at least 3 years. That alone should make us not want him there. Even after he leaves, it will take 3 more years for his players to wash out of the system -- see Stanford.