My biggest concern was that Mills would leave and we wouldn't have a back that could bring home the groceries. I think Frost's biggest mistake was deciding to bench AMart. Luke got a win against PSU (who was in the middle of working their own issues out), then got humiliated against the Illini who had his number. Did the offense have it's issues? Yes. Did Martinez average almost six yards a carry and complete over 70% of his passes? Also yes.
The difference in the offense's operation with a healthy Mills vs. injured/not available was marked. Stepp's addition was big. He's proven that he can effectively run the ball vs. P5 competition and he's a bigger back. He may not even be a lock to start, but he sets a baseline for competition in the room. NU win's every game but tOSU if it had a running game as effective as AMart's frosh year with Ziggy. I see the development of an effective running game as critical. I'm not worried about the passing game, nor am I really concerned with the departure of WanRob. Was he a good player? Yes. Really good? At times. There are a number of good pieces in the WR room and a core group will emerge over the Spring.
This is the B1G. If you run the ball, you can win. If you can't, you don't. It's that simple. If NU can run the ball effectively with the defense players it has, it can win in the B1G this fall.