Bynum's health is crucial to the rest of the series. He dominates the matchup between him and Perkins. I'd argue that when he's on(and that's incredibly rare because of his health), he's just as big defensively as Dwight Horward because he has the 7 foot tall Gasol helping him out. Seven blocked shots in game three. If Ray and Paul aren't on from the 3 point line, those two guys make it almost impossible to get good shots off when in the paint, and even tougher to get a rebound.
There is such a huge difference between Bynum and Odom, and you can tell by what Glen Davis did in game 4 without Bynum. Kobe will get his points, but I don't think the Lakers can win with Odom.