Boxscore-based player SPM ratings, representing the combination of production and effiency of a player. SPM means statistical plus-minus. Interpretation: The player SPM rating gives the scoring margin per 100 possessions for a 5-man unit consisting of the respective player and 4 average players (SPM = 0.00).
The rating is calculated by using all available boxscore data. It includes a minute, pace and strength of schedule adjustment. For the respective seasons there are three tables available: Regular Season (all games for the regular season included), Playoffs (only playoff games are included) and the overall page for that season with the table for the combination of regular season and playoffs.
Via the league average ORtg/DRtg SPM is converted into a Win% above average using phytagorean expectation (ORtg^14/(ORtg^14+DRtg^14) = Win%). Using the minutes played in comparison to the maximum minutes played possible to determine the player’s games a value for player wins above average will be calculated. After that the player wins an average player would generate in the respective minutes is added. That value is called Player Wins (PW). Divided by the minutes played and multiplied with 48 gives Player Wins per 48 minutes (PW48). An average player will have around 0.099 PW48 in any given year.
For the playoffs PW will not add up to the real amount of wins. That is supposed to happen, because the strength of the teams is determined by their performance level during the regular season and thus the strength of schedule will be in average clearly above 0, while for the regular season the SOS will in average be 0. That obviously will also have an effect on the combined version of regular season and playoffs, which is always presented at the starting page for the respective season.
Salary is based upon the minutes played, the performance level and the average player salary for the respective season. The average salary for each season can be found in the table below. There are no salary informations available for seasons before 1985 (at least not to my knowledge, if someone has the informations, please feel free to leave a message!).