Well Pedro does return today, and if he regains full strength, he is the best pitcher in baseball. I don't think I'd start him today because he is limited to 45 pitches so it will be impossible to get a win so why risk him getting lit up by the Cards.
RJ's situation is a little more concerning, because he has had setbacks on the knee surgery and won't be back until at least mid-July. If that timetable gets set back into August, which it likely will, the DBacks may well be completely out of contention by then. Rather than risk rushing him back, they might just shut him down for the season so he can come back at 100% next year. It won't necessarily happen, but you should prepare yourself for the possibility of not getting him back at all.
Basically, you have two lights out pitchers in Pedro and Oswalt, and RJ if he comes back. Behond those two pitchers, your pitching is very shaky. Maddux has been inconsistent all year and I think he is on a slow decline and won't be anywhere near vintage form this year. Foppert, Willis and Webb are all rookies, and I am not sold on the viability of any of them as fantasy pitchers for this year. Ride them while they're hot, but rookie pitchers usually go through huge ups and downs, and having to rely on three of them in your rotation is just asking for trouble. Eaton has also been inconsistent but is potentially lights out although he won't get many wins in SD.
Basically, depending on RJ's status, I do think your rotation is a problem. You might want to pull off some trades, because you could really use another solid starter or two. If someone is willing to give you a Morris, Hudson, Halladay, type pitcher for RJ, I'd do it and let someone else take the risk on him.