A new study of player-tracking technology has found that Chris Paul is the best perimeter defender in the NBA, while also producing more evidence supporting the defensive prowess of big men Dwight Howard, Tim Duncan, and Roy Hibbert.
The study utilizes data from the NBA’s player-tracking systems, which were installed in 2013 and provided scores of information for last season.
The authors introduced five new defensive metrics to glean information from the systems, in order to better understand the impact that players have on the defensive end of the floor. Volume score, or the total magnitude of attempts that an individual defender faces; disruption score, or the degree to which an individual defender is able to reduce the effectiveness of his assignment’s shots; and counterpoints, or a weighted average of points scored against a particular defender per 100 possessions, are three of the new metrics.
Paul, the starting point guard for the Los Angeles Clippers, was “the best perimeter defender in the NBA” in the 2013–14 season, according to the analyzed data. Paul’s matchups shot against him significantly less often than average last season, everywhere on the court, and when they did shoot they shot at a low efficiency. So he stopped players he was guarding from shooting as often as normal, and also guarded them so well that when they did shoot they missed more shots than normal.
“Paul, a league leader in steals, reduces opponents’ shot frequency more than any other player of his type” in the restricted area, the study authors said in a report due to be published in the Annals of Applied Statistics (PDF).
Alexander Franks and Andrew Miller, Ph.D. students at Harvard University, spent more than a year analyzing the data and coming up with the new metrics with the help of Luke Bornn, who is a professor in Harvard’s Statistics Department, and Kirk Goldsberry, a professor at the Institute of Quantitative Social Science at Harvard.
They submitted a paper to the Annals and are making a presentation on the advanced metrics at the MIT Sloan Sports Analytics Conference in Boston (PDF) this week.
“Their method snaked its way through every millisecond of the 2013–14 NBA player-tracking data set, and estimated who was guarding whom and when they were doing so. Then it quantified the performances of individual defenders for the season, in exciting new ways,” Goldsberry described in an article for Grantland.
An interesting visual representation of a defender’s impact on who he’s defending comes in a shot chart.
