Early Returns: SportVU Rim Protection Values

Oct 17, 2014; Los Angeles, CA, USA; Los Angeles Clippers center DeAndre Jordan (6) is defended by Utah Jazz center Rudy Gobert (27) at Staples Center. Mandatory Credit: Kirby Lee-USA TODAY Sports

Over the course of last season, one of the most interesting uses I found of league-wide SportVU data was the ability to estimate the rim protection values provided by big men.

Without going too far into detail (though read here if you are interested), the intent is to scale a rim defender’s contribution from what would be expected of a mythical “average rim defender” in the same minutes played and context by comparing the proportion of attempts contested and the the effectiveness of those contests by field goal percentage allowed. The value is expressed in terms of “points saved”, so for example the leader through the first segment of the season in terms of per minute value is Utah’s Rudy Gobert, who is contesting an absurd 73.3% of opponents shots near the rim (last year’s NBA average was around 38% with Roy Hibbert leading the way at 60.5%) on the way to providing over 3.5 points per 36 minutes of extra defensive value. To put that in further context, last year’s Jazz were the worst defensive team in the NBA. An improvement of the magnitude of Gobert’s contribution so far this season would (all else remaining equal) have made them roughly league average defensively.

With that bit of explanation out of the way and two-plus weeks in the book, it’s time to release the first set of numbers for this year. Several caveats apply:

1) Really small sample sizes. I don’t think Ersan Ilyasova is going to continue allowing 41% shooting at the rim for the remainder of the year, nor do I think Spencer Hawes will continue to be scored on at a 71% clip. The small samples also mean the “average” big is taken from last year’s data. Last night’s Wolves/Rockets game in Mexico was also not tracked, so data from those two teams will be slightly off.

2) Scheme plays a huge roll in “Contest%” one of the more important stats. Last year, power forwards and centers (broadly defined) had an approximately 11% gap between contest percentages, 44% for C’s and 33% for PFs. Hopefully that will forestall any “but Anthony Davis?!?” questions.

3) This is not Not NOT a measure of overall defense. Simply one (rather than the) measure of rim protection value. Many of the better big man defenders have value well outside this realm in terms of pick-and-roll defense, rebounding and so forth.

4) There are some odd names on the list and might be a few omitted (it’s filtered for players with at least 4 games played and 15 MPG on the season), this should sort itself out as the season goes.

So, without further ado, here’s what the data suggests just under 10% of the way through the season:

We’re working on automating this data so that it can be updated and found daily among our stats, but until we do that, I’ll post semi-regular updates.