Explanation of Composite Score - Basketball-Statistics.com

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Explanation of Composite Score

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, found at basketballvalue.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.

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.

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. Plus-minus can be found at basketballvalue.com and 82games.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)
DCS – Defensive Composite Score
DCS Rank – How a player ranks defensively among all the players in the league that qualify
CS – Composite Score (OCS + DCS)
CS Rank – How a player ranks overall among all the players in the league that qualify

Tips for Interpreting Composite Score Rankings

Take everything with a grain of salt. It may be weird hearing that coming from me, but it's true. If a player is ranked too high or too low in your opinion, try to think about why that is. Does he play on a really good team that inflates his numbers? Does he constantly draw the toughest defensive assignment, making his defense look bad? Instead of dismissing the numbers, try to think of why they are the way they are.
Look at a player's general range of ranks, not the specific number. If a player is ranked 10th, for example, I may not think he's actually the 10th best player in the league. However, I do think he's better than a guy ranked 50th. As always, think of the numbers as guidelines, and not as absolute fact.
Don't try to compare players based on their rankings. This is related to the last point. Because these numbers are an inexact science, and because the difference between two players is often extremely small, don't think that a player ranked 7th is automatically better than a player ranked 8th. It may be fun to discuss it that way, but it's not the best way to look at Composite Score.
Use supporting evidence. Look at my numbers, but also look at other advanced stats as well. Looking at all the numbers will give you a better overall picture of what stats say about a certain player.