He didn't struggle at Michigan he was a complete disaster, just like here.
The year Shafer was there Michigan was 50th in run defense, 87th in pass defense, 67th in total defense, 84th in scoring, 33rd in sacks, 38th in tackles for a loss.
Robinson took a torch to the thing. 2010 Michigan 95th run defense, 112th pass defense, 110th total defense, 108th scoring defense, 98th in sacks, 77th in tackles for loss.
That's not struggling, it's a barn fire.
That's as bad as the state he left the SU defense in two years earlier, where he was below 100 in every defensive category.