In the previous post we have established that referees in the NBA get calls correct in the most crucial part of close games 90% of the time or better. Fouls are snap decision and somewhat subjective (feel free to read this post on take down of basketball here). So for me this is a pretty good average. It should be noted that overall the league has improved in its call accuracy since 2015 (see Fig 1). This would indicate that measuring and reporting has improved referee performance. Smile friends, the NBA is focused on improving.
In this post we will explore the calls the refs get right and if the Utah Jazz are getting shafted. The main focus of calls are going to be the ones they call the most often; Personal, Shooting, Offensive, and Loose Ball Fouls.
Now, there are two sides to every call, the disadvantaged player and/or team and the other side is the committing player and/or team. Call accuracy distributions will be shown in a box plot below. I find these helpful to easily show the distribution of call accuracy for several categories at once.
In the below charts we can see that the majority of the Jazz’s calls fall within the distribution of the league’s call accuracy, from 2015-2018, aside from loose ball and shooting fouls. Again, call accuracy has improved over the years, but this does provide some evidence that the Jazz do not get the benefit on the doubt on these kind of fouls.
Now, this is the macro view… what does it look like year over year? Well, its improved. I will fully admit that this chart is a bit hard to read, but the trend for improvement is clearly seen from 2016 to 2018. This brings the call accuracy over 90%.
There is a more dramatic shift in the calls here, where loose ball and shooting fouls are far outside of the NBA’s distribution. However, we see the Jazz enjoy a much more accurate call for Offensive and Personal fouls.
In the below time series chart we can again see a dip and a return to accurate calls.
So… what? Well, to me this reads that the Jazz are at disadvantage vs the league overall. On the aggregate we can see they do not get the best treatment; and in some areas far below average. However, as reporting has been initiated, improvements to the leagues accuracy overall and as well to the Jazz has been seen. Transparency and accountability has improved the officiating of the game.