How do basketball teams win games? While searching for an answer to that question, Dean Oliver identified what he called the "Four Factors of Basketball Success":
- Shooting (40%)
- Turnovers (25%)
- Rebounding (20%)
- Free Throws (15%)
The number in parentheses is the approximate weight Mr. Oliver assigned each factor. Shooting is the most important factor, followed by turnovers, rebounding, and free throws. These factors can be applied to both a team's offense and defense, which in a sense gives us eight factors. Let's take a closer look at how these factors are measured, using the 2004-05 Phoenix Suns as an example.
The shooting factor is measured using Effective Field Goal Percentage (eFG%). The formula for both offense and defense is (FG + 0.5 * 3P) / FGA. For the Suns offense this is (3351 + 0.5 * 796) / 7018 = .534, and for the defense it is (3328 + 0.5 * 494) / 7485 = .478.
The turnover factor is measured using Turnover Percentage (TOV%). The formula for both offense and defense is TOV / (FGA + 0.44 * FTA + TOV). On offense, the Suns turnover percentage was 1125 / (7018 + 0.44 * 2080 + 1125) = .124, while on defense it was 1131 / (7485 + 0.44 * 1775 + 1131) = .120.
The rebounding factor is measured using Offensive and Defensive Rebound Percentage (ORB% and DRB%, respectively). The formula for offense is ORB / (ORB + Opp DRB), while the formula for defense is DRB / (Opp ORB + DRB). In 2004-05, the Suns offensive rebound percentage was 967 / (967 + 2550) = .275, and their defensive rebound percentage was 2652 / (1233 + 2652) = .683.
The free throw factor is a measure of both how often a team gets to the line and how often they make them. The formula for both offense and defense is FT / FGA. The Suns free throw rate on offense was 1556 / 7018 = .222, and on defense it was 1320 / 7485 = .176.