The problem at RB like you said is we have so much unknown, inexperience. We've seen flashes at time from Dwyer before being hurt and Batch before being hurt but we don't know if that will turn into solid play this year and if they can stay healthy, which unfortunately seems to be a recurring theme with a number of positions coming into this year.
We have some bigger pounders in Redman, Clay and even Dwyer at 230lbs, but we really need that homerun threat we seem to lack and even if Mendenhall returns this year who is to say what he'll have left, if may not be till 2013 that he is affective again.
A guy like Pead or James would be great but question is how early do we go after a RB, these guys will go in 2nd or 3rd, pushing other needed positions like OL/DL/ILB down further in the draft depending on where we go RD 1. Question is, will there be a back in the middle rounds that could suit our needs.