Said it on another thread, we only have 7 running backs who will physically be on the field to play at this point. For me, the lack of depth is a concern.
And while the RB core is thin, the defensive line just has thinner players. There isn't an eclipse like Humphrey this year. I realize somebody of his size doesn't come along too often, but he did plug a big azzed hole. I think the depth is there, but the lack of that one piece might have a bit of an impact.