Felix Jones would be an excellent guy to trade for, if he's available. But given his pedigree and the fact that Jerry went to Arkansas I don't see it happening. I'd give a 5th rounder for him this very minute. A fourth I'd think about but probably still do. He's not a feature back but he's an explosive presence in spots, a better player than Bush, in my view, but despite being the same sort of player still a weapon worth having, both in special teams and in special packages with Bush if you have an offensive coordinator creative enough to make it work.
Not picking him up because you have Slaton and Messam is the heigh of stupidty, IMO. The potential of former or current scrubs isn't worth the pixels fans spend on them. Much better for the team to invest in talent and figure out a way to use it than not see immediate way to use talent and therefore pass up on acquiring it altogether.