Dean Oliver (statistician)
Dr. Dean Oliver Ph. D (born 1969) is a prominent contributor to the statistical evaluation of basketball, or sometimes called APBRmetrics after the forum of a growing community of basketball analysts. He is the author of Basketball on Paper, the former producer of the defunct Journal of Basketball Studies. More recently Oliver has served in front office roles with the Seattle SuperSonics and Denver Nuggets of the NBA (including when the controversial trade for Allen Iverson was made).
Dean Oliver developed his work through a combination of technical studies and traditional basketball experience. He played Division III collegiate basketball at the historically win-challenged Caltech, graduating with honors with a degree in engineering there in 1990, and served as an assistant coach for the team beginning as a junior. He earned a Ph.D. in statistical applications in environmental science at the University of North Carolina in 1994 while scouting for Bertka Views, a scouting organization run by then Laker assistant coach, Bill Bertka.
He served as an engineering consultant between 1995 and 2003, continuing to do basketball research during this period, writing Basketball on Paper in 2002 and writing on Pro Basketball for About.com between 1996 and 1998. In 2004, Oliver set out to create a position in the NBA for statistical analysis, following the trend set in baseball, as illustrated by the Michael Lewis book, Moneyball, in 2003. By October 2004, he had impressively accomplished his goal and was hired as the first full-time statistical analyst in the NBA.
Among the areas of where he made contributions to the field are the following:
- Possession-based analysis, where possessions are defined as the period between when one team gets the ball to when the other team gets it. Teams are evaluated based on how many points per 100 possessions they score and allow, also called "offensive ratings" and "defensive ratings." The percentage of possessions on which a team scores Oliver calls "floor percentage", though it is a concept little used since what is ultimately most important is how many points are scored, not how often any points are scored.
- Four Factor Analysis. From possession-based analysis, there are four statistical team factors that summarize most of what matters in terms of winning or losing: effective field goal percentage, offensive rebounding percentage, turnovers per possession, and free throws made per field goal attempted.
- Individual possession-based analysis, evaluating the efficiency of individuals with their possessions. Oliver has presented his version of individual offensive and defensive ratings using a complex set of formulas and rough simplifying assumptions to parse credit among individuals.
- Bell Curve or Correlated Gaussian evaluation of teams. This is an extension of the well-known Pythagorean Expectation for relating team points scored and allowed to winning percentage. Oliver's techniques incorporate variation in points scored and allowed, as well as how much teams played up or down to opponents.
- Offensive and defensive scoresheets. Oliver has done significant work to track new data. He began his work by tracking how the ball moved from player to player. These were his offensive scoresheets and they formed the basis for his possession-based analysis. Later, he briefly constructed a group of volunteers to track defensive statistics at WNBA games. These statistics included field goals allowed, forced turnovers, and free throws allowed, providing more information than steals and blocks do on a player's defensive ability.
- Individual win-loss records. Oliver created two early ways of assigning wins and losses to players. One type is an estimate of a player's overall value. The other reflects the ability of a player to "do their role." The usefulness of the W-L scale as implemented is debatable.
- Head coach evaluation. Oliver did evaluation of NBA head coaches using a technique in Basketball on Paper that compares a coaching record to expectations. He admits that there are flaws in the technique, but it yields results showing that coaches can add as much as about 15% to a team's winning percentage (he has admitted making an error in the book, where the comments don't match the analysis).
- Referee evaluation. Oliver did a theoretical analysis illustrating that neutral referees who just make errors randomly introduce a bias favoring underdogs. This remarkable result shows that an error rate of 15% can cause a decline in winning percentage of about 5% for a good team.
- Risky strategies. Risky strategies are defined as ones that increase the variance of a score. In particular, Oliver shows that these strategies help an underdog and hurt a favorite. Examples of such risky strategies are using a press, shooting a lot of three-point shots, or slowing the pace dramatically.
- Roboscout. Roboscout is a tool that Oliver has hinted at in his works, but never released for any proof or review. In articles, he has written that it shows key aspects of a team or player to focus on defending. He has been quite secretive in how it works, but it clearly uses the Four Factors as its basis. Whether it goes much beyond that is unknown.
- Defense and winning championships. The phrase "Defense wins championships" is nearly ubiquitous in the sports world. Oliver has looked rigorously at this phrase in Basketball on Paper, showing that it has some validity, but not to great extent. Teams with good offense that have apparently relaxed on defense during the regular season and can ramp it up in the playoffs — those teams win championships.
- The Olympic Gap. Oliver documented that the world had nearly caught up to the USA in basketball ability over only 12 years between 1992 and 2004.