It's the problem that just won't disappear.

It's the biggest thing standing between Jim Harbaugh's football program and all the success everyone in it, surrounding it and supporting it wants.

Michigan's offensive line.

"(We'll) work on it," Harbaugh said Monday afternoon. "We'll get better at it."

It's a sentiment that's been repeated by U-M coaches and players for the better part of seven years now. They've shuffled bodies, changed staffs and tweaked systems. They've tried it all.

The latest example came Saturday at Wisconsin, as redshirt freshman quarterback Brandon Peters faced pressure on 13 of his 25 drop backs – his final attempt resulting in a concussion.

For the second time this season, Michigan saw its starting quarterback leave a football game before heading to the hospital.