Iowa shows a two-TE ace formation with two wide receivers to the boundary. Michigan is in its 4-3 under with Jordan Kovacs rolled into the box. Iowa will run an inside zone to the weakside of the field.
The key to this play is the block on Campbell and the weakside B gap (highlighted), where the play is intended to go. On the snap, Michigan's defensive line slants toward the weakside of the play. Campbell engages the playside offensive guard. The right tackle will get a free release to the second level.
Campbell has now been sealed to the inside despite slanting toward the play. He's gotten decent penetration, but the offensive guard is allowing him to get inside. Craig Roh is in the process of overrunning the play.
Despite Campbell's penetration, he hasn't kept gap responsibility because the offensive guard pushed him beyond the point of attack. Roh has been sealed to the outside. And the linebacker who was supposed to cover this gap (James Ross) has gotten a free-releasing offensive tackle in his face (Iowa's #70).
Roh and Campbell both reach to make the tackle but can't stop Mark Weisman who has a full head of steam.
And this is where Brady Hoke gets upset....
...because JT Floyd gets absolutely trucked and can't stop Weisman from picking up the first down.
This play starts with Campbell and the offensive guard getting playside of him. Campbell starts this play outside of the guard and, without any blocking help, allows the guard to seal him back to the inside. That's bad and that's why there's such a gaping hole here, but watching this play in contrast to Michigan's under-center runs highlights a stark contrast: Michigan doesn't create gaps like this. Despite the fact that Campbell doesn't play this particularly well, he's able to get good penetration and into the backfield, but the offensive guard helps him along, knowing that even if Campbell gets into the backfield, as long as he's kept to the inside, Weisman will have a lane to run through. Michigan's blocking schemes have confused the offensive line all season and may contribute to this lack of holes for running backs. Regardless, it's disheartening watching Iowa's mediocre offensive line able to create holes and separation for their running backs in ways that Michigan's line can't, but I'm hoping this is talent-related (Michigan's interior line is really weak) and not scheme-related.