By the time teams get to the finals, all the weak teams have been weeded out. By definition the top two teams in the league are decent rebounders.
The biggest stat to me is the point differential between the amount your team scores, and the amount your opponnents average. The larger the difference in your team's favor the better they are.
The Sixers this year are still a work in progress, they are not a consistent team, so it's hard to use the stats with any reliability. So far, they are a very good scoring team, but a poor defending team and a weak rebounder. The point differential is pratically negative, meaning teams score more on them then vice-versa.
If they can learn to rebound and defend, you'll see the improvement in that stat.
To me, the most important quality in a Championship team is not defense, it's having a player on your team that cannot be stopped. He will either score or get to the line at the end of the game. That's what wins championships, and why Center is the most important position. A player like AI can try to score at the end of the game, but get fouled and the ref won't call it, it happens so fast hardly anyone will see it, and the refs let teams play a bit more physical in the finals. Shaq on the other hand, or even Duncan, you have to hit with a club to make them miss. The refs will call that everytime.