I may be a little crazy, but I would keep D Williams, Greene, Fitz, and Welker. I know that every other poster will call me a douche, but with Welker practicing with full contact yesterday, I would just take the risk that he plays from day 1. With this being a PPR league, he has a lot more value (if it weren't, I think I would keep Benson instead). I like being a little ballsy (unless it is a high dollar league).
Disclaimer: If Welker gets re-injured or doesn't actually start the season on the active roster, I blame the whiskey in the morning