Such critical components of defense as positioning, communication, and the other factors that make Kevin Garnett and Tim Duncan elite on defense can't be captured, unfortunately. Blocks, steals, and rebounds, along with what little information offensive numbers yield about defensive performance are all that is available. This is not a great hindrance on the offensive side, as nearly everything of importance on offense is captured by the box score (only missing things like screen-setting), but on defense the box score is quite limited. There are limitations on all box score stats – if the box score doesn't measure a particular contribution, a box-score-based metric can only approximate that contribution. BPM does not include that data and should not be as accurate as stats that do include the additional information (assuming they are implemented rigorously!) like Player Impact Plus/Minus and Real Plus/Minus. Recently in the NBA far more statistics have been gathered, either from play-by-play or hand tracking, which allow more detailed metrics. The credit for getting that rebound mostly gets split among the team, rather than all being credited to the player who actually pulled the rebound down.īPM was created to intentionally only use statistics that are widely available and are available historically. They matter to the team, but it really doesn't matter who on the team gets them. Defensive rebounds fall into that category. Now, some of the box score data does not help measure a player's impact on the team, even though the stat may be obviously valuable to the team. Similarly, scoring by a low usage player has to be very efficient to mean much to the team, since they aren't putting pressure on the defense. For instance, a block by a center is good, but a block by a guard is great. This box score information is also weighted according to what position or role the player has on the team. Do they score more or less efficiently? Do they have more or fewer assists? Does this player get more or fewer steals than the other players on the team? If more, this player is likely better on defense than they are. All of the box score data is measured relative to the other players on the team. Next, the box score information is added to revise the evaluation. If the team is good, all of the players are assumed to be equally good. BPM starts by assuming that every player on the team has contributed equally. ![]() How does Box Plus/Minus evaluate players? The basic concept is simple. That elite team's best lineup of their five top players might be in the +14 range or even higher. Note that, by count of player seasons, there are far more below average seasons but that when you look at minutes played it is balanced.įor team scale, an elite team might have a regular-season team-level efficiency in the range of +8.0 per 100 team possessions. Here is a histogram of all player seasons from 1974 to 2019. ![]() 2.0 is a bench player (this is also defined as "replacement level") +0.0 is a decent starter or solid 6th man +8.0 is an MVP season (think peak Dirk or peak Shaq) +10.0 is an all-time season (think peak Jordan or LeBron) (In the 2018-19 season, teams averaged around 100 possessions per 48 minute game.) A value of +5.0 means the team is 5 points per 100 possessions better with the player on the floor than with average production from another player. Because above-average players play more minutes, there are far more below-average players than above-average players in the league at any time. League average is defined as 0.0, meaning 0 points above average or below average. ![]() ![]() BPM does not take into account playing time - it is purely a rate stat! Playing time is included in Value Over Replacement Player (VORP) which is discussed below. It is based only on the information in the traditional basketball box score-no play-by-play data or non-traditional box score data (like dunks or deflections) are included.īPM uses a player’s box score information, position, and the team’s overall performance to estimate the player’s contribution in points above league average per 100 possessions played. By Daniel Myers, developer of Box Plus/Minus, February 2020īox Plus/Minus, Version 2.0 (BPM) is a basketball box score-based metric that estimates a basketball player’s contribution to the team when that player is on the court.
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