That Hill had no concept of how to coordinate a defense. He was so concerned about only making sure his defensive backfield wasn't getting burned, that he didn't align the front 7 properly.

Jan said the linemen would roll their eyes when they saw the play calls.

On a different note, I did hear that he was good at teaching individual technique especially for corners. You can get away with being a "brick" if the players think they are getting better because of what you're teaching them. He lost that when he was in total control of the defense.