  This paper introduces a new model and methodology for estimating the ability
of NBA players. The main idea is to directly measure how good a player is by
comparing how their team performs when they are on the court as opposed to when
they are off it. This is achieved in a such a way as to control for the
changing abilities of the other players on court at different times during a
match. The new method uses multiple seasons' data in a structured way to
estimate player ability in an isolated season, measuring separately defensive
and offensive merit as well as combining these to give an overall rating. The
use of game statistics in predicting player ability will be considered. Results
using data from the 2008/9 season suggest that LeBron James, who won the NBA
MVP award, was the best overall player. The best defensive player was Lamar
Odom and the best rookie was Russell Westbrook, neither of whom won an NBA
award that season. The results further indicate that whilst the
frequently-reported game statistics provide some information on offensive
ability, they do not perform well in the prediction of defensive ability.
