If we're talking RB, I'd rather draft one than try and snag one as a FA. RBs have a shelf life of about 8 years in this league, so most of the guys available will be at least half way through it. Considering we've been decently successful so far with our late round picks Helu, Royster, and Morris, I'd prefer we avoided paying a bunch of money for a guy.
If we really want a top shelf back, I'd prefer Mike draft one with our 2nd rounder. RBs fall in the draft sometimes, and I'm sure Mike could find a guy in the 2nd or maybe even 3rd with skills he loves. Sure, it might take a year for the guy to reach his peak, but I'd prefer that, plus another 7 great years, than bringing in a guy for high price, and only getting 4ish years.
Besides, I still want to see how our current 3 pan out. Morris' only major knocks are that he's not super fast (but he's the same speed as Foster), and that he might not be able to handle 25 carries a game week in week out. Helu had trouble blocking, and was terrible after contact, but he looked like he shied away from contact less in pre-season. Royster might still be solid. I'd rather grow these guys, and maybe add another rookie, and spend big bucks on a safety, RT, or CB.