In my view a B is too high - principally because the team displayed an inability to finish the season, and because of the drubbing by Chicago... I also think B's too high because of the start that this team made, and some of the personnel choices early.
I give him a C grade. because despite my reservations above, he's done more than we expected, and was able to adjust mid-season, foster a collegiate team atmosphere and make the Bills exciting to watch.