The Value of Efficiency Stats in Basketball
nERD (numberFire Efficiency Rating Derivative)
The player ranking measures the total contribution of a player throughout the course of a season, based on their efficiency. League average is 0. Comparable to win shares, this ranking gives an estimate of how many games above or below .500 a league-average team would win with that player as one of their starters. For example, LeBron James posted an 18.3 rating in the 2010-11 season. If he played on a team with four league-average players, you would expect that team to finish 18 games over .500 (50-32). By summing the nF NERD for all players on one team, we can see how many games above .500 that team is expected to win. The rating will represent a player's total contribution over an 82-game season, not just the games played so far this year.
nF Eff
The numberFire efficiency metric measures a player's raw efficiency. More specifically, it is an estimate for the point differential that a league-average team would have with that player as one of the five starters. It combines both offensive and defensive production on a per possession basis. The main factors in determining a players' efficiency are usage rate (how many possessions that player uses out of the total team possessions - players like Kobe Bryant will have high usage rates, while the Shane Battier's of the world will have low usage rates), offensive rating (this combines basic statistics to estimate a players' offensive contribution per 100 possessions), and defensive rating (an estimate for the number of points an individual player would allow per 100 possessions).