I'm not a fan of rotation, especially '"mass" rotation and I'm going to stick to my guns. Put it this way if Rafa decided to rotate in the league like he did with Toulouse the other day, then I'd say we've got buckly's chance of winning the league. Changing between 4 and 9 players every other game will not win you the league IMO. I'd much prefer Rafa kept his "mass rotating" for all of the cups we're in this season but play a more or less settled side in the league.
But the problem Rafa has got is, keeping Mascha,Alonso,Momo,Crouch and players like Benayoun happy especially if anyone of them has found themselves out of the squad or on the bench for long periods. Although having a big squad full of good players is great, and Rafa's main reasoning behind rotation is the fitness levels come the end of the season. I think rotation is also a policy of keeping players happy over the due course.