Here's an article in Wired about a friend of mine, Dean Oliver, from elementary school who's now doing statistical analysis for the Supersonics:

After nearly every game, he produces reports for Sonics president and CEO Wally Walker, detailing patterns that elude traditional observation. This research was critical to the team's unexpected success last season.

...

Oliver thinks possession efficiency is basketball's version of on-base percentage. "Teams that score a lot of points don't necessarily win games, and teams that prevent opponents from scoring a lot of points don't necessarily win, either," he explains. "But if you convert a greater percentage of possessions into points than your opponent does, you win games."

You can check out his book, Basketball on Paper, or his site of the same name (he had more hair when I knew him).