Michigan didn't show a whole lot of new offensive formations against Northwestern, but they did debut the heavy I formation, which has two fullbacks lined up in the backfield:
This is obviously a short-yardage formation. In this instance, it's third and one about midway through the second quarter. Michigan is down 14-7 and has Steve Watson and Stephen Hopkins lined up as fullbacks. Fitz Toussaint is lined up deep as the half back. Northwestern is predictably loading the box.
Just before the snap, Watson takes a step forward and another step to his left, which seems like a horrible idea. This tips off the Wildcat linebackers as to what direction the play is headed. You can see in the screen below that the Northwestern MLB (or possibly strong safety, I can't tell) starts moving toward the A gap because Michigan has tipped their hand.
As the ball is snapped, you can see the linebacker is already at the line of scrimmage and about to engage Watson in the A gap. For a play that is designed to get one yard, creating a log jam at the point of attack is probably not the best idea.
Watson has now engaged the linebacker and is falling over. Hopkins is headed into the same hole as a lead blocker.
By the time Toussaint gets the ball, Northwestern has changed the line of scrimmage at the point of attack. Because the linebacker was able to key on Watson pre-snap, the Wildcats have plugged the A gap and pushed the Michigan blockers a yard behind the line of scrimmage.
Toussaint dives into the hole and fails to make the first down. After a few timeouts, Michigan would eventually make the conversion on fourth and one with a QB keeper.
This is MANBALL of the worst variety. If Watson doesn't motion pre-snap, he likely hits that linebacker a yard beyond the line of scrimmage instead of at the LOS. Hopkins then doubles that linebacker or finds someone else to block and Toussaint easily picks up the one yard. But as we'll see later today, there's a reason for this: Al Borges' diabolical machinations.