There seems to be a correlation between when Ray stinks, and when the whole team stinks.
I hate the term X-Factor but Ray is that for this series. Kobe is athletic enough that he can sag on Rondo for long enough that he is forced into Gasol and Bynum. If Ray can get off the screens and get open it forces Kobe to shade him. That forces the Celtics into too much pick and roll and the Laker's are frontcourt can move switch.
C's need someone to draw a double team and open the Laker's defense and create some space for ball movement.