You're right with Jackson and with Donald Brown out I'd put my money on Vick Ballard. Greene has been hotter than usual lately but Powell is still getting 10-12 carries a game and a lot at the goalline so there's a good chance for a letdown there. McFadden is fresh off the injury and facing a very good Broncos defense so he is not worth the risk. Jackson and Ballard are a good combination of low risk/big upside for you.