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Utah Jazz center Rudy Gobert, ΔD, and his path to greatness

The Gobzilla is real. And we needed a new statistic to help explain his dominance.


This season the Utah Jazz are climbing their way up from nearly tying a franchise record low for wins. Of late the team is much more capable on the road and a big part of that has been improved defense. And a huge part of that has been Rudy Gobert. There are normal stats out there which try to quantify how good he has been, from his rim protection to his rebounds. But I had to throw my hat in the ring too. Rudy Gobert, all 22 years of him, is a defensive juggernaut. And thorough ΔD he is third best All-Time in New Orleans / Utah Jazz history – and taking over the NBA.


Delta Defense:

This is an explanation on the stat. TL;DR version is that:

  • It measures who is a defensive finisher (like an offensive finisher).
  • It doesn’t mean you are a great individual defender, but it doesn’t mean you are not one either.
  • It is inherently a bigman stat, and favors those who are the most overt causes of possession change on defense.

There are different theories on defense. Some say defense is simply stopping the other team from scoring. Others feel like defense is only complete after the possession has changed. There are box score stats that show defensive events, but may mask poor defense (gambling isn’t good defense, but if you are conservative you don’t get the stats). Advanced stats attempt to quantify greater goals, while perhaps being limited to linked factors. And ultimately when trying to gauge an individual player’s own defensive abilities we lose sight of the truth that defense is a team goal and the success or failure of it lies with the team.

I made the Gestalt Offensive Rating seasons ago, offense was easier to understand, measure, and report. There is no Gestalt Defensive Rating because we do not openly track all aspects of defense. Individual teams look at charges drawn, deflections, and shots changed. Few people measure passing lanes denied, or position denials. And for me the ultimate defense is one that goes undiscovered on a box score. If you are good enough at defense the man you defend will be forced to pass the ball, but not to a man in scoring position, to someone else because you have ultimately disrupted their game plan. The best defense does not register a charge, or missed shot, or steal, or whatever. The best defense is so encompassing that there is almost no record of it at all unless you watch the game.

For me I have tinkered with defense before, with the Defensive Gambling stat (which attempts to measure a player’s ability to successfully gamble on defense and get a steal or block, as opposed to a foul); and with the Pure Hustle stat (which incorporates defensive grittiness, but also with getting offensive rebounds, and so forth). Both are nice stats but don’t completely explore what we see because of a lack of reliable stats. Pure Hustle should include guys diving on the floor, or getting 2nd or 3rd jumps on 50/50 balls, but no one records that. Defensive Gambling needs to factor in if the other team scores on one of your gambles, and not just if you foul on the play. As the inventor of these stats I am well aware of their flaws, Gestalt Offense doesn’t track people who set screens on offense; yet it should.

So I bring to you all another stat today. They aren’t classically "advanced", I place them in "Calculated" as a category. My stats involve a lot of calculations and ratios, looking at NBA trends, averages, and player performance. It’s Delta Defense, or simply, ΔD.

For me it’s important to recognize that your team can play good defense, but perpetually be playing good defense with no end in sight. Good defense is denying the passing lines, pushing guys out of position, preventing dribble penetration, and challenging shots. But that good defense doesn’t successfully complete the main objective: getting the ball back. Defense becomes successful when your team is no longer on defense anymore.

This happens either when the team scores on you (bad), or when you get the ball back (good).

The defense doesn’t rest until they are on offense again.

So ΔD is the change from defense to offense. Or more reasonably, the individual change that occurs on the floor when a player is on defense. You can be a poor individual defender, but still contribute to finishing the defensive play. Similarly, you can be a great defender, but not get on the stat sheet for your efforts. ΔD rewards the people who make the stat sheet, but don’t exactly have to be the best defenders in the land. Why even go through all this effort to figure this out? Well, because I have to say that sometimes being there to finish a play is almost as important as being there to set it up. I laud Karl Malone so much as a finisher, while also giving John Stockton props for starting it. To avoid being a hypocrite I have to give their due to both the good defender and the defensive finisher too!

Sometimes they are one in the same, other times they are not. A classic example of this would be how Kyrylo Fesenko would be the defensive bigman back in the RMR, and he would body up their post player and challenge their shot. Kosta Koufos would clean up the play and get the defensive rebound. Fes didn’t get the block, or anything on the stat sheet – while it was him who was the guy actively playing defense. Kosta got the board to end the defensive series. If not for his work on defense then someone like Fes would be playing defense all over again. If I can look beyond my Fesenko-philia to see the value of what Kosta was doing (while getting all the stats), then I feel like I’m a better person.

And ΔD helps understand this new idea that defense isn’t over when the shot is missed. Defense is over when your team has the ball back.


Calculating ΔD:

Just like how Northrop Grumman isn’t going to go out there and tell China how to make Stealth Bombers, I’m not going to show you all of the work. But ΔD is a related rate compared to production over time. So it removes any bias of skew from someone who may play more minutes and thus hog up a lot of stats. Of course, if you only play in garbage time your stats are going to be inherently funky anyway, so there’s not much I can do there. But if you are regularly getting over 10 mpg then it seems to work out perfectly.

The formula finds rates of production for defensive rebounding, blocks, steals, turning the ball over, and fouling. It individually calculates the rates a player has (for a career or season) and adjusts that against normative NBA means for those factors. A more complicated version of this was being devised that gave bonus points for reaching certain values, but man, I have a life. No really, I do.

These five factors are then plugged into an equation that incorporates things like what percentage of a players total rebounds are on defense (DGLASS%), or how good their hands are (with respect to assist to turn over ratio, and if a steal is a good steal or not). [Ed. Sometimes you can get a steal, and feel good about yourself, and then have the ball stolen right back. This happened a week or two ago in a Jazz game where some bigman stole the ball from Gordon Hayward. Hayward stole it right back. The big guy would normally be on the books for changing possession twice, but really only once. A bad hands guy getting a steal isn’t as good as a good hands guy getting one.] So each of the five factors have many additional calculations to them that look at NBA trends, NBA averages, and weight. Blocking a shot is nice, but there’s no assurance that your team gets the ball back. Mark Eaton blocked a lot of shots, and the Jazz got the ball back because John Stockton was there to collect it. Getting a defensive rebound is more reliable in ΔD, as a result.

But if you must see the final calculation it looks like this – where the parent cells are far removed from being simple data.

Delta D - Calculation

No really, I have a life . . . I swear!

Quickly, for bigmen an average ΔD score is between 4.00 and 6.00. Below that is, obviously, a tire fire. When you get to 7.00 you are "good" in my books. A 9.00 is "great", and the closer you are to double digits makes you one of the best. Some players score well above double digits, and that just shows how amazing they are as a defensive finisher.


Getting back to Rudy Gobert:

Rudy Gobert is our best defender. This isn’t a ΔD thing, this is the eye-ball test. The eye-ball test helps us form opinions on if something makes sense or not. We like Derrick Favors too. We’re less crazy about Alec Burks as a post defender. You get the picture. The first test is to see if ΔD works with the eye-ball test with our current (2014-2015) Utah Jazz squad.

Delta D - Utah Jazz 2014 2015

So Jeremy Evans, the anomaly, is #1. He rules all advanced stats, so who didn’t see this coming? But Gobert is #2 on the team, and clearly on the right side of 10.00, and thus one of the best. Favors is right behind, and then there’s a huge drop off. Two win players are high up (Gordon Hayward and Joe Ingles), and that’s cool to see. No doubt it’s because a HUGE proportion of their total rebounds are defensive rebounds (DGLASS). So that even goes to show you how dominant the three bigs ahead of them are – they get dinged by having a DGLASS value under 70.00%, but still lead the team.

On first blush I would say that ΔD makes some sense. Trevor Booker is "good", while Enes Kanter is actually an average defensive finisher. (Again, ΔD doesn’t mean you are individually good on defense, it’s if you are a good component to a defensive system / team defense.) Elijah Millsap is scrappy, but he’s clearly not a bigman. And clearly this stat that is skewed towards bigmen doesn’t help him.

But what about how this stat looks compared to the rest of the league?


2014-2015 NBA Leaders in ΔD:

If it passes the eye-ball test for the Jazz that’s one thing, that’s a small sample size for a group of (by the boxscores) poor defenders. What about the best defensive bigmen in the league? Let’s take a look:

Delta D - Best Bigs 2014 2015

ΔD means you are a defensive finisher on a team that is playing defense (of some sort). And more than that, it means you are at least getting the stats that LEAD to a change from defense to offense. I think it’s obvious that ΔD seems to match up well with our idea of who those defensive finishers are. And, oh, look at that! Rudy Gobert is Top 15 this season, and Derrick Favors is almost in the Top 20.

I feel like ΔD has been demonstrated as a valid calculation which finds players who get defensive rebounds, block and change shots, and get steals – while factoring in how much they hurt their own team with fouls, and so forth. Players like Kevin Love and Al Jefferson (and Blake Griffin) aren’t regarded as great defenders – but they finish plays on defense. (The Koufos to the Fesenko from the RMR example.) While guys like Tyson Chandler, Anthony Davis, and Al Horford also score high here (good defenders who also get stats). These are some of the best 30 bigmen in the game today on defense (I undervalued how well Tobias Harris is doing, as a wing player / tweener, but the numbers don’t lie).

And it feels great that the Jazz have two players (aged 22 and 23) amongst them! But wait … there’s more!


If ΔD is legit, how do these two players compare to the four plus decades of Jazz basketball:

So far 257 different players have played for the New Orleans / Utah Jazz franchise. I know. I spent this weekend doing data entry where I now know that Robert Smith (6 games) has a 7:0 assist to turn over ratio, or that Delaney Rudd has 4 blocks in a Jazz uniform. (I don’t think other Jazz bloggers do this much work for a post that will get zero recs and 4 comments.) Among that entire group not all of them were power forwards and centers (duh). Also, 8 of them played most or part of their careers before turnovers were recorded: Freddie Boyd, Nate Williams, Aaron James, Paul Griffin, Jim McElroy, Gail Goodrich, Pate Maravich, and Rich Kelley. That is in addition to the 22 players who played without ever recording a turn over: Walt Bellamy, Rick Adelman, Henry Bibby, Stu Lantz, Bernie Fryer, Jim Barnett, Louie Nelson, Mo Howard, Bud Stallworth, Andy Walker, Ollie Johnson, Russ Lee, Ken Boyd, Lamar Green, E.C. Coleman, Toby Kimball, John Block, Ron Behagen, Mel Counts, Otto Moore, Neal Walk, and Rick Roberson. Furthermore, there are some players who played during the era of the "all of the stats era" that we’re currently in, but just didn’t record some key ones, like Keon Clark not having a turn over, or Brooks Thompson not having a single rebound, and so forth. For some players the calculation just wouldn’t work because they didn’t play at the right time, or didn’t play enough.

I was able to successfully calculate ΔD for 218 of the 257 Jazzmen. Very few of those numbers are Hall of Fame material for the "Small Sample Size Hall." But if you remove all the guards, and some of the small forwards who weren’t overtly SF/PFs . . . and then get rid of all the people who didn’t play at least 1,000 minutes for the Jazz . . . you get a much more workable group of 55 players.

Delta D - Best Jazz Ever 1

Delta D - Best Jazz Ever 2

So….. for their cumulative careers Rudy Gobert is outperforming Mark Eaton as a defensive finisher. That’s gonna ruffle some feathers, even if this measures finishing ability – and Big Mark was more of a primary defender. But more on that in a bit . . .

Some names missed out by the 1k minutes cut:

  • Andris Biedrins (ΔD 9.4538, 45 minutes): Somehow without getting a single block or steal, he managed such a massive value – all on defensive rebounding. I wish him well
  • Trevor Booker (ΔD 7.1713, 724 minutes): He’ll be on the full list after this season for sure
  • Kosta Koufos (ΔD 5.7089, 737 minutes): The Koof today is a lot better than his younger version. In an attempt to legitimize his defensive contributions somehow he is merely just average.
  • Josh Howard (ΔD 5.3955, 991): Josh ranks between Michael Ruffin and Kent Benson. Bravo, you were all-free agent mercenary 1st team in my book, though.

Al Jefferson has been fantastic as a defensive finisher, which I think works well with what we know about him. Very low turn overs, so his steals mean more. He got a high percentage of his rebounds on defense, and got a lot of rebounds. He blocked shots and didn’t foul. If you add it all up he was a tremendous defensive finisher. He caused a lot of change on the court. The same could be said for Truck Robinson. And I don’t think that anyone will argue that Andrei Kirilenko, Karl Malone, or Carlos Boozer weren’t adept defensive finishers. But Rudy beating Mark . . . let’s take a closer look.


Mark Eaton’s season by season ΔD:

Perhaps this is where we see being a great defender isn’t the same thing has having a high ΔD?

Delta D - Mark Eaton Season by Season

Rudy Gobert’s second season is would be higher than every individual season for the 2 time DPOY except for his massive 84-85 season. Just that Mark played 34.3 mpg that year, and Rudy is at 20.7 mpg. Playing good defense and making a huge impact in big minutes helps build your rep. Rudy needs more minutes to build his rep . . . but at the age of 22 he’s having a huge season. If Mark Eaton is the Utah Jazz center litmus test then this is a really positive sign for Gobert.

But let’s bring it all home . . . let’s look at the rest of the 2013 Draft Class bigmen . . .


The 2013 NBA Draft: 1st round bigs only:

Now in their second season we have nine first round bigmen who have played this year. Eight of them were picked ahead of Rudy Gobert. Anthony Bennett went #1, and five other centers went in the lotto: Cody Zeller, Alex Len, Nerlens Noel, Steven Adams, and Kelly Olynyk. Lucas Nogueira was picked right out of the lotto, and Mason Plumlee was snatched five picks before Rudy.

Guess who is winning the ΔD competition?

Delta D - NBA Draft Class 2013 Bigmen

It may be anti-climatic to show that Gobert’s season performance is Top 15 in the entire NBA right now, and better than most of Mark Eaton’s career, and his cumulative career numbers in a Jazz uniform are 3rd best in franchise history . . . but I had to show him against his own draft class to put it in perspective.

Rudy is only 22. He’s in his second year. He could end up being the best Defensive Finisher in franchise history. If you compound that with the fact that with the eyeball test he is already our best defender . . . . sheesh. Most stats show how big Rudy is. He is a man of numbers: his height, his length, his age, and his on court production. But he is just so good so early. And when it comes to ΔD he is out of this world.



The true peer group for Rudy could one day be the All-Time best paint defenders. This goes beyond the four plus decades of this franchise, or his draft class. While players like Bill Russell, Wilt Chamberlain, and Kareem Abdul-Jabbar played parts of their careers in eras before blocks and offensive rebounds were even recorded – we do know that the career ΔD’s for Dikembe Mutombo was 11.46 and Hakeem Olajuwon was 10.03. They both played 18 years in the NBA, and are at the top of almost everyone’s list for best bigmen defenders. Time will tell if Rudy Gobert will ever become a Hall of Famer big. But right now it looks like his on-court production makes it someone we can track.

Utah Jazz HD Wallpaper - Rudy Gobert GOBZILLA