The interview: a conversation with an anonymous RealGM legend about new-age player tracking data, advanced stats, and the Golden State Warriors.

Insight into the intersection of machine learning and player tracking, the limitations of traditional defensive metrics, how player tracking data rates the defensive impact of Warriors, and more.

Before NBA Twitter, before Reddit’s r/NBA, and before team-specific Discord communities, there was RealGM. The basketball board on RealGM has well over 40,000,000 million posts dating back early 2000s and I found RealGM and its famous trade checker as a pre-adolescent. It was there on RealGM that I made some of my dumbest, pre-teen observations about a game that I thought I understood and started to realize just how wrong I often was.

One of the fun things about RealGM is the wide range of opinions you encounter. There are plenty of trolls and reactionaries on the General board. I don’t recommend spending much time there. But every now and then, a forum rando with less than 10 posts will make an astute observation on the General board that opens your eyes. If you pop into the Trade and Transactions board, there are plenty of salary cap geeks and numbers guys who cite interesting data to reject or accept imaginary proposals. Sometimes Ben Taylor of Thinking Basketball and Backpack Picks fame — known as ElGee on RealGM — will drop historical knowledge on the Player Comparisons board. Over on the Warriors board, Evan Zamir, one of the more ornery characters on Warriors’ Twitter and the creator of the legendary NBA WOWY database, will dole out his takes about the draft or the Warriors’ rotation. 

This is all to say, there are credible people on RealGM if you know where to look. Sometimes these posters disappear into the shadows, like the random user on the Warriors’ board who alerted us pre-game that David Lee’s 2010 elbow infection might be more severe than was initially let on. There also was a poster that accurately predicted Jason Kidd leaving the Brooklyn Nets for the Milwaukee Bucks two days before the national media wrote about it. And then there’s FNQ.

Since 2006, FNQ has been one of the most fair-minded and intellectually curious members of the Warriors’ board on RealGM. FNQ, whose real name we won’t use, is a smart guy who has worked in the medical field and he gained a lot of credibility in my eyes when he hinted at and accurately assessed that Monta Ellis’ was probably lying about an offseason ankle injury he suffered shortly after signing a 6-year deal with the Warriors. 

For those of you that don’t remember, Ellis initially claimed that he’d injured his ankle in a pickup basketball game. Based on the nature of the injury — a torn deltoid ligament and high-ankle sprain —  FNQ was pretty sure that this injury was the result of a low-speed motorcycle incident. You can see some of those posts here, here, and here. Note that the dates on these posts pre-date confirmed reports that Monta actually injured his ankle on a moped. 

So FNQ is credible and if you trust my judgment, then you’d probably be interested in some of the things he’s been saying on RealGM over the course of the last two seasons. FNQ has ended up working with or in proximity to two different companies that specialize in applying machine learning and human analysis to player tracking data about the NBA. One of these companies, to whom he no longer has any connection, was using fast-frame cameras to track shot form. The other company, whose work will be the focus of the majority of this conversation, has some very interesting revelations about player defense.

This tracking data, FNQ says, is far more advanced and reliable when it comes to capturing defensive impact than catch-all adjusted plus-minus stats. FNQ’s thoughts and opinions about this Warriors team have fascinated me all season, particularly in regards to what the data he sees is telling him about the defense of various Warriors players, so I reached out to him to see if he’d be willing to talk — as much as he can without giving away proprietary information — about what he’s learned about this Warriors’ team. This conversation has been edited and condensed for clarity.

K: So I’m 28 and I’ve been on RealGM since I was 11. You’ve been there for the majority of the time that I’ve been posting on that board. My memory is that you’ve been in the medical field for the most part. When did you transition over to data science stuff and when did that cross over into basketball?

FNQ: After the Warriors’ second championship, I started thinking I’d done the medical thing for a while, but it’s taxing on the mind and you deal with the worst of everything. I’ve always loved basketball and when I love something I want to understand it and understand how it works. So that was my journey into data science. I thought, “I’ll do some fun stuff for myself with basketball,” and I started looking into advanced stats, so I’d check the APBR forum for basketball (Association for Professional Basketball Research), and I’d check RAPM and those types of stats. 

Once I started going into data science, I realized that I could make something up and see if it works and try it out. I got really into it and I started going into data science with SQL’s (Structured Query Languages) and machine learning models and things of that nature. It just so happens that one of the people that I was in a class with five or six years ago had a connection to this new advanced thing with basketball where they were taking Second Spectrum data and other tracking data with all these new cameras that capture by frame how someone is shooting, where they capture passes — really obsessively detailed stuff. 

They weren’t just processing it through a machine to get a result as a number, they were doing analysis with it — they were getting objective and subjective information. And the end of the day, some of these older advanced metrics are amazing at telling us results but they do lack context. They don’t tell you what position a player was in; they don’t tell you who was at fault; they don’t read defenses that great; they can kind of hint at who might be at fault on defense, but they can’t really tell from play to play who has been breaking things down. 

The one example we go to all the time on the Warriors’ board on RealGM is Kelly Oubre. He broke down our defense quite a bit because he didn’t know where to go. But if you look at his defensive metrics, they weren’t that bad compared to James Wiseman who was very, very bad himself. But was Wiseman as bad as Oubre? It’s hard to say based on metrics alone. The tracking data gives you a better chance of breaking that down and seeing things play to play because it’s impossible for anyone to pick it up on a first, second, or even third glance sometimes. If you want to look at a play really well, you have to look at it a bunch of times. This new way of looking at sports science is hopefully going to catch on — for someone like me, this shit is like crack. 

K: So I’ve actually pointed a few people at your posts on RealGM about this. One of the things that interested me about your posts is that the data you’re evaluating is both objective and subjective and I’m curious what you think are some of its strengths and limitations. A few years back, Grantland published an article about the Dwayne Casey-era Toronto Raptors, who were using a “ghost defense” program that would evaluate what the Raptors would do and overlay “ghost defenders” over their defensive film and show them what they should have done. I’ve thought about that article lot in the context of the data you talk about. Blown rotations — sometimes it’s obvious, right? But how does a machine or how does a program determine what constitutes a blown rotation? Do you feel like there are any significant strengths or flaws that need to get worked out with these systems?

FNQ: That’s where the subjective part comes in. I objectively won’t be able to figure that out looking at the box scores and metrics. Someone has to be watching the game and saying, “ok, where’s the first breakdown?” It’s hard to assess blame sometimes. The evaluators will evaluate it in all sorts of different ways... some people see things that sometimes aren’t there. When I am watching games, I’ve missed so many defensive rotations — you’ve seen me post in the game threads sometimes, “oh shit, somebody blew it,” and then they show it in slow-motion and it turns out I was dead-ass wrong. 

You can’t keep up with everything. There’s always a possibility of human error but so far the results that we see from the player tracking really are what we see on the court. It’s pretty linear, especially when it comes to defense. It’s way better to evaluate defense that way. With offense, I think you can get a really good view just by looking at the metrics and making an analysis. EvanZ on Realgm, he’s amazing with numbers. He can make an impeccable read on someone’s offense — 100%, I’d believe it. Defensive wise? I don’t know. I know he loves metrics but I don’t trust metrics by themselves. There’s always more to it. There’s a context that defensive metrics can’t pick out that well. 

K: So two interesting revelations you’ve doled out on RealGM have been your opinions about Andrew Wiggins and Jonathan Kuminga on defense. Even though he’s shown a lot of pop as an on-ball defender earlier in the year, what you’ve been saying consistently is that Kuminga is responsible for an inordinate amount of defensive breakdowns relative to the minutes he plays. Is that correct?

FNQ: Yes. And I will die on that hill for a couple of reasons. He doesn’t always miss rotations, he’s just late a lot of the time. The 4 and 5 position for the Warriors is so tough. The Warriors’ defense has really thrived when they’ve had our three best defenders — Wiggins, Draymond Green, and Kevon Looney. The Warriors rebounded well and they did everything really well because they have three guys who are really smart and know each other and know where they’re going to be. Kuminga isn’t necessarily making the wrong reads or doing everything too slow — it’s that the other guys don’t trust him to do the right thing so they might make the wrong rotation because he hasn’t moved somewhere yet. 

The one thing that I see the most with Kuminga is the backdoor cuts when he’s on the baseline. He doesn’t always know if he’s staying with the screener or following his man. Then the person that’s coming in and following the screener, they don’t know where Kuminga is going and then they make their call based on that. That happens a lot to Jordan Poole, by the way. Poole will throw his hands out and say, “what the fuck?” 

That’s not necessarily an indictment of Kuminga or Poole going forward. Player tracking models can’t really tell potential. Potential is such a wild variable that I don’t even try to get into it that much. I can only really tell you whos’ good right now versus who is not good right now and then you look at their numbers, like say, Kuminga’s pull up-numbers. Does he have potential as a pull-up guy? If you look at his numbers for the entire season, I’d say, “no, probably not,” but If I look at the second half of the season, he looks a lot more respectable. We saw it in the past couple of games — he made a couple of pull-up jumpers. 

Kuminga has definitely got a lot of potential but the defensive issue he’s going to have with the Warriors is that 3, 4, and 5 are the three of the most complex parts of our defensive system as currently constructed. They might change it later to accommodate him or our roster later, but as of right now, he’s a rough fit for that system. He doesn’t have the basketball IQ to really do well there and the other guys don’t fully trust him. And that’s absolutely fine! He’s a rookie! You can put Otto Porter Jr. in that same situation and he’ll have a lot of the same struggles. So I’m not trying to really bag on Kuminga or highlight him like that, I just don’t want the Warriors’ fanbase to start to bag on him next it starts to become evident next year. That’s what we do with every rookie! Eric Paschall wasn’t that good in his second year and people wanted to cut him; Jordan Poole and Draymond Green struggled as rookies too, let’s cut them!

K: So how about Andrew Wiggins? I think most people are past the point of calling him a bad defender. It’s very obvious that what was going on in Minnesota on defense has no bearing on him as a Warrior but I still see a lot of complaints about his off-ball defense. But if I recall, you’ve said that the tracking data bears out that off-ball defense is one of the things he does best as a Warrior. 

FNQ: That’s correct. It’s definitely what he does best. I know that he does pretty well on the ball — in fact, I’m pretty sure that ESPN looked at some similar tracking data and found that Andrew Wiggins is the #1 defender at the small forward when he challenges a shot. Anytime that he’s the closest defender and he’s challenging a shot, that shot goes in at a 39% rate. To veer off a little sideways, one of the reasons I talk a lot on RealGM about Franz Wagner is that the tracking data says that he’s up there with Wiggins as a defensive small forward. He’s super young, but I’ll double, triple, and quadruple down on this: I’d rather have Franz than Kuminga and I still really like Kuminga, but god, Franz is good. 

But circling back to Wiggins; this dude covers so much ground. One of the things that player tracking first started covering was how much distance these players would travel. Wiggins dominates that metric for the Warriors on a per-minute basis. He’s switching, he’s really good at closing out, and what he does that I really love when he’s off-ball is that he doesn’t guard defenders’ backs. You’ll probably see this a lot in the Denver series — you’ll have Jokic in the middle, a guy in the weakside corner, and the ball is on the strong side. 

The weak defender is now crawling up Jokic’s back and that gives Jokic an easy post up and the defender is now out of position to guard the three-point shooter in the corner. It’s one of the things that drives me nuts — what are you doing? You either front Jokic to prevent that whole thing from happening or you sag off and try to let Looney or whoever try and guard the ball and Jokic. 

If you guard the defenders’ back, you’ll give up so many open corner threes. But what Wiggins will not do is guard the big man’s back — he’ll stand kind of in the middle but he’s not selling out completely to guard the man in the middle and he has enough time to get back to the corner and challenge the three. So he does things like that and he’s excellent at switching too. If you ever watch him and Draymond switch, you’ll notice there’s hardly any communication or any yelling. If you ever go to the games it’s easy to hear Draymond because he yells nearly every possession, but he’s not yelling as much when it comes to Wiggins. They know and they have that connection, especially defensively. 

Another part of it is that while I do think Wiggins is great and bordering on elite of-ball in terms of the entire league, when compared to our other defensive options at the guard — Steph Curry, Jordan Poole, and Klay Thompson — all three of them are really questionable off-ball. Steph is probably the best of the three off-ball, but he’s used to guarding flat-footed shooters and small forwards who are just 3+D guys and we’d normally put Klay on the ball. So that would normally leave the small forward like Oubre, Wiggins, Durant, Iguodala, or Barnes to cover the most ground. Wiggins is perfect for that. So every time we don’t play him off-ball or we put him on a premier guard, like say, Devin Booker, or a healthy Jamaal Murray, it’s not using Wiggins or the Warriors’ defense to their full potential.

K: To that point, in the lead up to Klay’s return, a lot of people assumed it would be best to position Klay off-ball or put him on power wings or 4’s to keep the load off of him physically. But now in the context of these stats and the tracking data that you see, my understanding is that Klay has been pretty damn good on-ball, all things considered, but that the airhead and space cadet tendencies are still damaging off-ball. 

FNQ: His on-ball defense is the anti-Gary Payton. He’s not waving his hands to try and make guys uncomfortable — he’s just smart. He never lets his man cut back to the middle, he’ll funnel them to the side where hopefully there’s someone waiting and he doesn’t really get beat off the dribble that much. He does more than he used to, obviously, but he’s still really good on ball and I think in terms of how the Warriors play their best, I’d put Klay on ball all the time. It puts Jordan Poole in the Curry role — here’s someone easy, don’t fuck it up — and then Wiggins and Draymond doing the yeoman’s work and really keeping it together, and then Kevon Looney is the wild card. Looney on Jokic is way better than the league average on the post!

K: I think that the Warriors’ internet community has really crystallized their appreciation of Kevon Looney this year. I think him playing 82 games has made people realize how crazy it is that he’s here and one thing I wanted to bring up is your posts about Kevon Looney. My understanding is that Looney covers a lot of ground and that’s a key part of this Warriors’ team’s defensive system. I remember you making a direct comparison between Looney and Jakob Poetl saying that Poetl’s rim protection stats were somewhat inflated by the Spurs' drop coverage whereas Looney’s rim protection stats were more impressive because he covers a lot more ground than most centers. Am I remembering that correctly?

FNQ: If you put Looney in the Spurs’ system, he’d still be good, but Poetl would probably be better for that team because they have a drop system where you drop below the screen and they have these long, rangy defenders like Dejounte Murray, Lonnie Walker, Derrick White before they traded him, and Devin Vassell. Looney definitely covers more ground than someone like Poetl, and his defensive role at the center is definitely more rare. I said this in a post recently; I don’t think people are ready to have a conversation about how valuable Looney is to the Warriors. Is he part of the Warriors’ best lineup? No, that’s the Death Lineup, the lineup of the assumed top 5 players that are probably going to close the game. But in order to get to that point, to get to that point where the Warriors are still in the game going against a Jokic, an Ayton, an Embiid, or Gobert — one of those monster 5’s — you have this 6’9 guy who got drafted as a 3/4 who is now the Warriors’ starting center and he’s holding these 5’s off. If the Warriors lost Kevon Looney, what happens? 

K: So we’ve barely talked about offensive stuff, but I recall you saying that you guys have pretty good metrics on shot form.  I distinctly remember you bringing up Gary Payton II shooting like shit when he looked down at his foot.

FNQ: Yes, so the shot stuff was this company that would try and capture the same angle of the court every time with cameras. They would look at maybe 5 to 10 games and they would look at each shooter’s shot each time and they would look at release point or see if a defender affected the shot form. If, for example, a defender didn’t affect the shot, that makes it a “normal” shot that counted into their little system and they’d try and find how out much of this is repeatable — how many times is a shooter doing the same thing over and over again? If you have a very repeatable shot, then you have a better chance of being better! 

With Gary Payton II, the company actually highlighted him because in the summer league we wanted to get some data on players, but we didn’t have any data because these were mostly summer league players. Gary Payton was the only guy that we had any data on so followed him exclusively and got data on every one of his shots in the fast-frame camera. We were looking at his mechanics and his shot form was very different than it used to be. At the end of the 2020-2021 season, his shot form was very random. But in the summer league, he was shooting a little catapult shot every time and it was beautiful! It carried on into the beginning of this regular season and he started off shooting very well from three. 

As you’ve seen me say on RealGM, when he looks down — I don’t have a metric for this season because I’m not with that company anymore and I’m just counting on my own now — his shot percentage goes way down. It’s better to make a long two than it is to miss a three, so just take the shot where it is. But he just has this habit of doing that. At least he’s not pulling a Pietrus and stepping out of bounds, so he at least gets the shot up. 

K: I want to circle back to a few things that you alluded to but we didn’t fully get into. You implied that are lower on OJP as a defensive player than the general public. My general read on him is that he puts together one or two games every few weeks where he moves laterally enough to say up with wings, but is otherwise pretty weak as a point-of-attack defender, but quite solid as a weakside defender. Does that line up with the tracking stats?

FNQ: Generally yes, but more specifically with regard to his off-ball defense, he's great at some aspects, and lesser at others. When he's playing a big position, usually paired with Draymond instead of Nemo, he's a much better help defender. When he's in a big position with Nemo, his help defense is much worse. And when we occasionally play him as a big SF, he's fine there too.

K: Here’s another one; you mentioned fatigue being a potential issue for Wiggins' mid-season regression and the Warriors' defensive regression in the absence of Draymond Green. What insight can the tracking numbers give us on how Wiggins' defensive role changed without Draymond and the downstream effects that had on the Warriors' defense?

FNQ: Without Draymond, there was no one there directing traffic and no one making all the smart plays inside, so it was like playing with an incomplete lineup. Much like if we lost Wiggins for an extended period, our perimeter defense would suffer. I don't think Wiggins is as important as Draymond, but he's a notch or so below, which is still very key for us. When Dray was out, Wiggins had to play a lot of Dray's position, and when he did, he still played like the 'perimeter' defender more than the 'interior' defender that Dray typically is. He was moving all over the court more defensively and we were a lot worse because we not only lost Draymond, but we essentially lost the benefits of what Wiggins brings on the perimeter too. And that cratered our defense — since we've had the Dray/Wiggins combo back, our defense has looked much better, and that's a trend that we should carry into the playoffs.