I believe that there is no reason whatsoever to make substantial moves at RB prior to working free agency and the draft. We first need to try to flip the defensive line into at least a strength on paper--- not depth but a weapon! Any move sooner than that I would hope is caused by Murray deciding he really wants to stay to chase a ring at the cost of striking a Cowboy and Murray-friendly deal. If his sights are set on what the market is for him, I am good with that. Let him shop.
I would rather roll with an above average defensive lineman and an average RB than the opposite. If we can do both, fantastic but I'm shooting at the D line first.