No, he didn't play against us. He was injured, and Nick Sheridan started for them. He had around 200 and a TD. They also mixed in Justin Feagin quite a bit, and even though everyone in the stadium knew he was exclusively going to run, we still couldn't stop him (much like Kafka the week before, though to a far lesser extent).
As for the impact on Michigan, I don't think they'll be any better/worse off for him leaving, considering who they have returning and coming in this fall. If I were a Michigan fan, I'd greet this news with a shoulder shrug and a "eh."