If he could get a few minutes per game if Pierce is struggling or TA is, it'd be a huge help in my opinion.
Meh... even when PP has struggled in this series, he's generally been playing pretty good D on LeBron (at least as good as we could reasonably expect from Quis). TA's been pretty consistently good on the defensive front as well. Since Quis hasn't been giving us much of anything in terms of scoring or playmaking since... well, since before he got hurt, I'd rather keep the rotation tight and have those minutes go to Pierce, TA, and Ray Allen.
Playoff basketball means that your eight best players get 98% of the playing time. I don't see how Quis is anywhere close to being one of our eight best.
EDIT: I'd say, too, that Rondo's exceptional play (and huge minutes) is impacting Quis as well. If Rondo's not playing as well and as much, maybe there's a need for another guy who can handle the ball.
As of right now, though, it's really a four-man guard rotation. TA kinda fills in as the backup at all three spots. Amazing to see how much TA's finally improving, particularly with respect to being able to contribute consistently.