I agree with Rich that the large rotation is more the result of inconsistency rather than the cause. MS and BA have played some great games off the bench this season, as has JG before he was starting.
If you look closer at the minutes, there are 5 clear leaders in MPG averaging between 23 and 31 minutes. After that 5, the next guy drops down to 18.7 (and that is JC – who could be under 15mpg by the end of season if the current trend continues). BA and MS are barely over the 15 minute threshold (under 16 for both) – so I don’t think those numbers are as dramatic as they appear.
It’s easier to have a small rotation if you are playing well and you can ride the lineups that are succeeding, but if Reed never knows what he is going to get game to game, I agree with his philosophy of throwing different guys out there until he gets the effort and production he is looking for.