I'm not a hater but I think Willis lacks definition as a back (not body defnition), he sways back and forth from either being a power back or a cut-back finesse style runner. When he is one, he is not the other and both characteristics are never on the field at the same time. He wants to be a power back when holes are opening and a finesse back when the OL sucks. It would seem to be vice versa, run with power when there aren't many holes and be a finesse back when there are.
There have been posts floating around regarding the new NFL and now it seems that teams are going to a 2 back system, given that they have a decent OL. More and more it seems with a solid OL any back can put up decent numbers.
I think the HB position in general is going to be less revered as a skill position in coming years (LT aside of course), how many backs gain 1000 yards per season now? I think it was 15 or something last year, it used to be a monstrous accomplishment.