Ray's had one decent game against Philly, going 7-14 for 17 points in the Game 2 loss. Overall, his offense this season has been tepid (36 points on 31 shots in 126 minutes). Allen has been average to poor in every other facet of basketball besides shooting for a while now, and his play this series hasn't changed that.
Doc really doesn't have many other options, with AB playing with one arm, and the rest of the littles (Dooling, Sasha, Moore, and Quisy) marginal NBA players at best.
So Doc is going to play Ray 30 minutes and hope that, at a minimum, the threat of him catching fire from three will space the floor and allow opportunities for other, like in Game 3, when Ray got up only one shot in 25 minutes but the Cs had a huge game offensively.
I'm not going to disagree that Ray looks like a shell of his former self this series, but he's being a gamer. I'd rather have Ray Allen hopping around on one leg than the alternatives at Doc's disposal right now.