Notre Dame actually did a pretty good job defending against Michigan, and I would argue that defensively that they are the closest to what we are defensively that Michigan has played so far. (Our line and overall secondary is better, the Irish arguably have better linebackers.)
The reason Notre Dame lost to Michigan is that their quarterback got hurt in the first half and Notre Dame got down by two touchdowns-- also, the new golden boy ND coach made a stupid decision not to kick a field goal before half time. Even with that, though, they still probably should have won that game. I thought it was a funny that a lot of the same illegal holding and chop blocking that Michigan did against Indiana got called against Notre Dame. I wonder why?
Also, Indiana's defense makes me cry. Their secondary may be worse than Michigan's, and that's saying something.
I'm actually really looking forward to the Michigan game since it is such a contrast in styles. If our defense plays bend but don't break and our offense asserts itself I like our chances.