Another aspect of Dean Oliver's Four Factors is Turnover Percentage or in short-hand, TOV%. This is a gauge of the percentage of possessions ending in turnovers, so it is a little more nuanced than just counting the total number of TOs.
How to calculate TOV%
TOV% = TeamTOV / (TeamFGA + (0.44 * TeamFTA) + TeamTOV)
While this metric is useful in a single game setting (to uncover why a team took more/less shots), it becomes a more impactful data point when sampling from more games over a season. As the analysis considers more teams with different paces, strength and strategies, the true tendencies of an athlete or team will come through in the stats.
Why you need to track turnover percentage
We can review two teams from the 2018-2019 Eastern Conference playoffs. As of May 9th, 2019, the Toronto Raptors and Milwaukee Bucks had the following team stat lines.
Toronto is averaging one less turnover per game, so one may assume they are protecting the ball better. However, when we look at the data in terms of TOV% or percent of possessions that end in turnovers, the results are a bit different.
(Toronto Raptors) 11.5% = 12 / (83.2 + (0.44 * 20.1) + 12)
(Milwaukee Bucks) 11.4% = 13.1 / (88.8 + (0.44 * 27.8) + 13.1)
Obviously, this is not a significant gap, but it demonstrates why it is important to view turnovers as a proportion rather than a single counting stat.
NBA teams have been embracing this factor as well. While it may not get the same publicity as "shot selection" and EFG%, it is an extremely important metric to follow for a team as well as their opponent. Jared Dubin for FiveThirtyEight recent profiled this topic and found that the league-wide decline in TOV% mirrored that of the league-wide increase in EFG%.
Fewer turnovers = more shot opportunities
The idea of winning the turnover battle is not a new one. However the strategies implemented to reduce strategies and increase FTAs and FGAs are new. More transition possessions, more spacing, quicker shots in the half court, combined with defenses that are not putting themselves in awkward positions by going for steals. All of these created a way for offenses to turn the ball over less, shoot more 3s, and score more points.
"You miss 100% of the shots you don't take." - Wayne Gretzky
As Hall of Famer Wayne Gretzky once said "You miss 100% of the shots you don't take." This is just as true in basketball as it is in hockey, and by reducing turnovers you can take more shots.
At Pivot, we are incorporating the TOV% as well as several other tried-and-true basketball metrics, such as offensive and defensive rating, into each of our applications. Detailed descriptions can be found here: