I would float the idea that Pop should semi-shut Manu and Tim down the rest of the regular season. The logic is:
1. The Spurs are not, say, the Hawks. The aren't looking for a good deep playoff run to build for the future. Their sole goal is to win Duncan another ring.
2. For the first time this season, there is feeling of a (still small) chance of actually pulling it off.
3. The only thing that will definitely move the chances back to impossible is injury. The reward for getting a 4th or 5th seed is not worth the risk of injury.
4. The priorities should be, in order:
a. Keeping Manu and Duncan healthy
b. Getting Parker back into synch
c. Getting everyone (esp RJ) enough just enough playing time to keep the gears oiled
The benefits of doing 4a-c is that you would also get some good reps from Blair, Hairston, and yes even Mason, which might actually come in handy in 1-2 crucial moments in the postseason.
The risk, of course, is that the Spurs would go into the playoffs rusty and having lost some momentum. But at this point I'd prefer to have them come in healthy, KNOWING what they are capable of, and maybe a little cold, as opposed to the worse-case scenario of pushing Manu 35+ minutes to eke out 1-2 more regular season wins and having him get hurt.