Meh... you could, but I think both have just about as much a chance as contributing as the other. I think McKinnon at least serves as an Asiata handcuff (as weird as that sounds), so I might go that route. Kind of depends on the structure of your roster. If you have Foster, I'd keep Blue. If Asiata is your third back or worse, I'd keep Blue. If Asiata is your RB2 or RB1, then I'd grab McKinnon.