One of the main problems that analysts and fans have with talking about defense in the NBA is that there really aren’t great metrics for it.
On offense, it’s significantly easier to parse out responsibility; giving credit for a stop on defense is tricky. If Klay Thompson funnels an under-sized player into the waiting arms of Draymond Green, who gets the stop, it will show as Thompson getting beat, and Green as single-handedly getting the stop.
But that’s not how defense works.
This is a big reason why we don’t talk as much about defense as we do offense: it’s just a lot harder to objectively quantify impact. Beyond that, given the limitations inherent in this endeavor, I’m not at all convinced that there will ever be a singular defensive metric that’s worth much.
And that’s fine, honestly. Using simple box score-based statistics like blocks and steals, in combination with more advanced metrics like DRAPM can start to give us an idea of the value of defenders. But taking a look at the advanced stats from the NBA, the current state of data present a pretty reasonable (if incomplete) list. I think that the answer here may actually be to include more new ways to look at defense, rather than trying to hammer the data into one number.
Enter the visual solution?
What if, in addition to focusing on traditional defensive impact metrics, we were able to use player matchup heights as a proxy for versatility? And if this information were available for multiple teams, then perhaps it could add to the conversation about defensive players in a meaningful way.
What stands out?
Here are the frequencies of defensive matchups for the Warriors, broken down by opponent height. You can see right away the Dubs' vaunted interchangeability and versatility, with similarly sized players defending opponents up and down the spectrum. (cc: @thecity2) pic.twitter.com/J0znreoDpm— Positive Residual (@presidual) March 2, 2018
Obviously, this is just a partial picture of defensive value, but cross-checking this against standard Defensive Rating (DRTG) leads to some interesting insights.
Draymond Green, Shaun Livingston, and Andre Iguodala
Draymond Green’s line here doesn’t surprise me, but the bias towards playing against taller players does. It may be a personnel issue (where our wings are probably assigned smaller players more often), or perhaps an efficacy issue (related to Green’s amazing proficiency covering the post)... but whatever the reason, it’s notable that Green almost exclusively matches up against taller player.
Shaun Livingston was the player who made me want to write this article. A lot of fans — including members of this community — frequently call for Livingston’s proverbial head. “We need bench shooters!” is a specific shot at Livingston’s game. Although he only plays about 15 minutes per game, Kerr and the rest of the Warriors’ coaching staff treat him with kids gloves — often resting him, and praising him at every opportunity. In fact, when you search the NBA league stats for DRTG, Livingston is twelfth - above Igoudala and Green. Now, prior to looking at this image, one could easily be led to believe that DRTG is “broken” - but taken in context with the graphic I’m beginning to think that maybe there’s something more than nostalgia involved with our team’s commitment to Livingston.
Along those same lines, Andre Iguodala’s wide swath of defensive responsibilities deserves some attention here as well. A defensive specialist and “glue guy,” Iguodala has a reputation for being able to do a whole lot on the defensive side of the ball and this graphic just shows what many of us already recognized: he really can cover anyone.
Try and remember this next time you are tempted to bemoan the lack of three-point shooting from our bench — the guys who aren’t shooting are on the court for a good reason.
A look at some other interesting teams
Yeah, I know this is a Warriors blog, but I found some of the other teams’ graphics to be interesting enough to warrant out attention here as well.
Here are the Rockets defensive matchups by opponent height. We can get a sense of the range that Luc Mbah a Moute and Trevor Ariza have when it comes to shorter opponents, as well as Chris Paul with taller opponents. pic.twitter.com/yDSQAMtDUE— Positive Residual (@presidual) March 2, 2018
The Rockets entire team is built around putting flexible defensive wings (and lots of shooting) around James Harden. Looking at this graphic, it becomes abundantly clear why Houston can be a tough matchup for the Warriors. As stated in the original tweet, Trevor Ariza and Luc Mbah a Moute are incredibly versatile, working well against players both larger and smaller. Remember too that this is just a graphic of coverage by height though, NOT prowess. So looking at a player like Chris Paul covering taller players is probably as much of a function of his diminutive stature as it is any sort of favorable matchup. Same goes for Ryan Anderson, a tall wing player who will naturally tend to be paired off against shorter players.
For comparison, here are the Spurs defensive matchups by opponent height: pic.twitter.com/nHUxMKuDA3— Positive Residual (@presidual) March 2, 2018
Just a couple of quick thoughts on the Spurs - a team struggling to maintain playoff legitimacy without star Kawhi Leonard. For one, it looks to me like most of their matchups don’t reach too far into other heights. Leonard has a relatively short band of heights that he covers - but it isn’t clear if this is due to lack of versatility (like if he struggles against really tall, or small and fast players) or due to system design (due to coach Gregg Popvich’s desire to stick him on opponents best wing player).
Dejounte Murray is another interesting player. At 6-foot-5 and playing point guard, it looks like there’s a natural trend towards him covering smaller players. However, it seems like Popvich is comfortable using him in a variety of assignments, as you can see that his bars of coverage extend quite a ways, indicating that he is slotted/switched onto taller players fairly frequently.
Not the whole picture
I hope this was informative, but as discussed at the top, these pictures don’t capture everything. Hopefully creative analysts will continue to generate interesting new ways of capturing and visualizing defensive impact. Moving forward, it seems like the best move will be towards accepting the fact that there’s no one catch-all defensive metric. Rather than fighting the statistics to try and wrestle one from the data, perhaps more diverse analysis will be the best path towards clarity when discussing defensive impacts.