IMO the one that hurts the most in Givens. It would have been very nice to have his quickness in the middle, and more depth there going into next year. That said, it's possible that Hansard and Mustipher could team up to become a force in the middle with more bulk than we've had there in a while. We will see.
As for the rest, I'd say in order: Bates, McGovern, Sanders, Miller
Bates was a cowbell in the tackle spot, and probably our best lineman the past 3 years. That one will hurt a bit too, but from all reports the new young lineman are really stepping up in practice to push teh first string. Add McGovern there too, although I think he was a better center than guard. He missed some key blocks this year, felt he was better last year.
I do like Boobie, but just think we are loaded at that position and something (Slade most likely) will step up. With a year under his belt and some good weight room work he could be a beast next year.
As for Miller, I think it's the same as the RB position. There's a ton of young talent there and I feel Miller might have been pushed out of playing time next year anyway.
It sucks to lose guys early though, but in this case I think it's mainly depth.
In big games - OSU, Mich and MSU
The offense with the the 3 that are leaving could not get crucial first downs late in the game (OSU, MSU) or much of anything (Mich).
The defense with the 2 that are leaving could not get crucial stops (App St., OSU, MSU, Kent).
Will we lose 4 or more games again next year because these 5 left??