Explanation of Composite Score Player Rating System
By Jon Nichols
The Composite Score rating system consists of two components, Offensive Composite Score (OCS) and Defensive Composite Score (DCS). Each is made up of a combination of three advanced statistical metrics and then adjusted based on a player’s position and playing time. The rating system is always under construction, so the system used today may not be as good as one you could see in a few weeks.
First, let me explain OCS. It is a combination of three statistics: the Offensive rating system developed by Dean Oliver (which can be found at basketball-reference.com), PER production (found on the team pages at 82games.com), and offensive plus-minus, also found at 82games.com. I then adjust offensive rating and PER production for position. Next, I add up the three z-scores for the three stats for each player and multiply them by 10. After adjusting for playing time (whether or not most of it is against starters or benchwarmers), Offensive Composite Score is complete.
Offensive ratings are an incredible measure of efficiency. PER also measures efficiency but takes into account players with higher usage rates. +/- is a great indicator of how well a player is fitting into his team and helping them offensively.
The average score is set at 0.
* -40 and below: Terrible
* -40 to -20: Very bad
* -20 to 0: Below average
* 0 to 20: Above average
* 20 to 40: Very good
* 40+: Elite
Player rank percentiles were also included to get a relative value of each player. When determining a player’s position, I merge small forwards and shooting guards, because they are often interchangeable.
Next is an explanation of DCS. DCS uses the mirror statistics of the three used for OCS. Instead of Offensive rating, it uses a very similar Defensive rating. Instead of PER, it uses counterpart PER, which is basically the PER accumulated by a player’s defensive matchups. Finally, instead of offensive plus-minus, I use defensive plus-minus. The scores are on the same scale as OCS.
Composite Score (CS) is a combination of OCS and DCS.
Plus-minus stats, counterpart PER, and PER were found at 82games.com. PER, or Player Efficiency Rating, was developed by John Hollinger. Offensive and defensive ratings, which were developed by Dean Oliver, were obtained from basketball-reference.com. Player names and positions were obtained from dougstats.com. I used an adjustment for starters based on the formula developed at the APBRmetrics message board (http://sonicscentral.com/apbrmetrics/index.php).
Glossary of terms on stats pages:
OCS – Offensive Composite Score
OCS Rank – How a player ranks offensively among all the players in the league that qualify (at least 500 minutes played)
OCS % - The player’s offensive percentile rank (for example, a player ranked #1 has an OCS % of 100%)
DCS – Defensive Composite Score
DCS Rank – How a player ranks defensively among all the players in the league that qualify
DCS % - The player’s defensive percentile rank
CS – Composite Score (OCS + DCS)
CS Rank – How a player ranks overall among all the players in the league that qualify
CS % - The player’s overall percentile rank
*Stats were calculated about a month ago, and that they'll be updated in another month or two.
Comments are greatly encouraged and can be sent to firstname.lastname@example.org.