Which running back would you start in a fantasy league? Knowshon Moreno or Joseph Addai?

I have a solid starting running back but I'm in a league where you start 2 running backs. Addai is a great running back but he is going to be splitting carries with Brown. Knowshon Moreno was a good college RB and now with the broncos losing their star quarterback and their star WR questionable Moreno may get a bulk of the work, but he's an unproven rookie at the moment. See my dilema? What are your suggestions?