Illinois wasn't actually picked to do well this season. Their non conf was the surprise, not as much where they are now. I think we are the top surprise--picked last, totally unknown team with unknown players. PSU was expected to be better with Frazier back. Northwestern had some returning talent off a decent team, but a new coach.
I think it's pretty much us and, voila, Michigan in the top two surprise slots (Michigan lost a ton off that team last year. No one thought they'd do this well).