How to tell if someone is a good rim protector

Last season, the New Orleans Pelicans were dead-last in opponent rim accuracy (per Cleaning the Glass). And after they used the draft to address some of their outside shooting woes, they should now look to use free agency/off-season trades to fortify their interior defense.

As fans of the team, it is always fun to follow along in the process and identify some players that could potentially be strong candidates to fit the roster’s needs. But good rim protectors are a little bit trickier to identify than good shooters, so how can a layperson go about evaluating that specific skill?

Well, the first (and most important) part of the player analysis process revolves around watching film. You need to watch the games to get the proper context on the environment each player is/was playing in.

But on top of that, you also need to combine your film-binging with some statistical inquiries. After all, the data sees every possession. In this post, we’re going to give you some good statistical indicators for assessing a player’s rim protection abilities.

A simple yet effective way to measure a player’s rim protection ability is to look at their block percentage (BLK%). In his 2014 novel, “Basketball Analytics: Spatial Tracking”, Stephen Shea identified block rate as a strong indicator of a player’s rim protection prowess.

As with most of these statistics, you’re going to want to look at a player’s BLK% relative to their peers (so what percentile were they in) in order to account for era-adjusted inflation. A great tool for doing this is Cleaning the Glass because it separates players based on their position. So, you can see how a center’s block rate compares to other big men (we are going to be focusing on bigs because they are typically the ones who provide a majority of a team’s rim protection).

For instance, if you look at our Pelicans, none of their “bigs” finished higher than the 62nd percentile in their position in block percentage. The player who finished in the 62nd percentile was Jaxson Hayes, who only played 610 minutes this season. The big-minute guys like Jonas Valanciunas and Larry Nance Jr. only finished in the 39th and 43rd percentile, respectively. Do you see why we struggled so much in this facet of the game now?

Another good statistic to look at is NBA.com’s “DIFF” metric. This statistic tracks the field goal percentage a defensive player “forced” an offensive player into with their contest compared to their expected average on that type of shot. For this measure, the more negative someone’s “DIFF” is, the better.

For instance, Brook Lopez had a DIFF of -13.2% on shots inside of six feet (per NBA.com). That means that he held players to 13.2% below their average on shots he contested inside six feet of the rim. Other prominent guys who score highly in this metric include Giannis Antetokounmpo (16.7%), Walker Kessler (-13.1%), and Defensive Player of the Year (DPOY) Jaren Jackson Jr. (-12.8%).

One last statistic we can look at is how much a team’s opponent rim frequency varies when a certain player is on/off the court. This is another Cleaning the Glass feature. And the reason we are looking at it is because the best rim protectors are the ones that not only do a great job of contesting shots, but also are so menacing inside that they deter other teams from taking shots in the paint altogether. It’s great to be able to turn a 65% shot into a 55% shot. But it’s even better to just make sure that shot never gets taken in the first place.

Anyway, a player who consistently grades out particularly well in this category is Draymond Green, who has been in the 92nd percentile or higher in on/off opponent rim frequency every season since 2015-16 (so eight straight years).

To recap, we’ve cited block percentage, DIFF (within six feet of the rim), and on/off opponent rim frequency as some statistics to look at when evaluating rim protection. Those aren’t the only measures that can be used to ascertain a player’s skill level in this particular area. But using those three (combined with copious film-watching) will give you a pretty good idea of just how good of a rim protector someone is.