It's pretty obvious to me that Bynum is the key to Pau playing well against the Celtics. When Bynum is active and mobile, the Lakers rule the paint, get the Celtics' bigs into foul trouble and get lots of easy looks. That also keeps the ball moving on offense for the Lakers, as Pau is a very willing passer. And even Kobe can't resist the easy lobs to Bynum.
With Bynum out, the mauling of Pau starts about 18 feet out, and he rarely gets good position. Rasheed and KG drive him nuts with constant pawing, bumping and jawing. Big Baby can't go over or around Pau and Bynum together, but he can get around Pau solo pretty well. KG can score in any manner of ways when he has the extra room to move - Odom can't bother his shot, and Pau can't keep him out of the paint. Basically, with Bynum reduced to about 15 mins of play last night, the Lakers' game devolved to bad jump shots and free throws. They did pretty well with that, 'cause they have Kobe making incredible shots, but I think the Celtics have their number now. Their D is just ridiculous, and they've found enough ways to score on the Lakers to get it done, even if they make huge numbers of appalling flubs. Perkins running the break? Fouling Kobe on a 3? Not to mention all those bobbled layups.