Crazy, I was going to post some speculation like this. I noticed the shot of him rubbing his left shoulder on the bench last night.
But also, remember when KG punched Dwight Howard in the arm twice last series? Dwight put his hand TWICE on the same spot that KG massaged last game. It's possible KG reacted that way because it really hurt him...
Like others have said, it would affect his rebounding and ability to elevate his left arm.
Now we really must get our stories straight, is it his knee, his shoulder, or his
WAIST because
THAT's where Dwight was putting his hand?
Oh, and I agree with kozlodoev, grabbing rebounds with one hand has been typical for Garnett, which is one possible reason his rebounding with the Celtics has been less than overwhelming statistically. Not a complaint, just a fact.