Quarterbacks had a hard time against Michigan last season due to a pass defense that finished second in the Big Ten. If the Wolverines are going to compete with Ohio State for a conference title this year, a similar defensive performance will be needed, since there are a number of solid quarterbacks on the schedule.
Last season, Michigan didn't allow a single 200-yard passer until the 33-28 loss to South Carolina in the Outback Bowl. Impressive may be the word you're looking for.
The Big Ten isn't known for wonderful quarterback play, but there are a few flashy players who can keep any defense on its toes. Michigan better be prepared for a two-headed monster in Northwestern and two other quarterbacks who rushed for 1,000 yards.