Six weeks ago a couple of Kirk Goldsberry’s Harvard University colleagues presented a paper at this year’s MIT Sloan Sports Conference in Boston. The paper focused on the lack of data to analyse defensive performance. It’s very easy to measure a player’s impact on offense, they argued, but aside from tallying blocks, steals and defensive rebounds, a typical NBA box score gives us very little to go by.
The paper goes on to discuss the new wave of advanced metrics and player tracking data that is emerging to assist in assessing these impacts.
It got me thinking… how can we best go ‘beyond the box score’ (as I did recently with the MVP race) to determine who have been the best defensive players this season and who deserves DPOY recognition?
With the regular season done, we know that Anthony Davis led the league in blocks per game, Kawhi Leonard paved the way in steals, while DeAndre Jordan grabbed the most defensive rebounds. But while those three, along with Draymond Green, Andrew Bogut, Tim Duncan, Rudy Gobert and Nerlens Noel are all in the conversation, are they all really deserving of consideration? Let’s find out.
Firstly, it should be noted that no wing player has won the DPOY award since Ron Artest with the Pacers back in 2003-04. In fact, since the award commenced in 1982-83, there have only been seven occasions when a perimeter player took home the hardware and five of those were in the first six years of the award’s existence. That means that over the past twenty-six years, only two non-forward/centres have taken this honour.
Is something wrong with that? You betcha. Three of the five players on the defensive end of the court for every team, every night are wings or guards. In fact, with the trend towards the use of stretch 4s and spread offenses, you could argue that number is four of five who play defence predominantly on the perimeter. Clearly there is bias towards big men given the immediate gratification of a stop resulting from a block or defensive rebound. Let’s see if that is fair or not.
I looked at 9 different advanced metrics, but have discussed 7 [1] that give the best indication of a player’s defensive impact. Unless otherwise indicated, all stats were taken from basketball-reference.com as of the completion of the regular season.
A quick explanation of these metrics before analysing what they mean for the DPOY race;
Defensive Rating: An estimate of points allowed per 100 possessions.
DWS (Defensive Win Shares): An estimate of the number of wins contributed by a player due to his defence.
DBPM (Defensive Box Plus/Minus): A box score estimate of the defensive points per 100 possessions a player contributed above a league-average player, translated to an average team.
Defensive Rebound Percentage: An estimate of the percentage of available defensive rebounds a player grabbed while he was on the floor.
Steal Percentage: An estimate of the percentage of opponent possessions that end with a steal by the player while he was on the floor.
Block Percentage: An estimate of the percentage of opponent two-point field goals attempts blocked by the player while he was on the floor.
Rim Protection (grouping of 3 metrics): I utilised data from nyloncalculus.com (via nba.com/stats) that looked at Rim FG% Allowed, Contest % and Points Saved per 36 minutes.
Defensive Rating: This metric belonged to Draymond Green for a large chunk of the season, but Kawhi Leonard has swooped in to take honours here.
The Claw’s rating of 96.4 is well clear of the next best player, Andrew Bogut (96.8). Tim Duncan 97.0, Green 97.2 and Rudy Gobert 98.0 round out the top 5.
Leonard’s impact defensively is on full display with this metric as he is a relentless harasser of the ball, gets his giant mitts into passing lanes and at the rim. It’s no wonder he leads the way here.DWS: We looked at Win Shares in the MVP race. Defensive Win Shares is essentially the same, but only takes into account the player’s defensive impact and how that translates to the win-loss column. You’d have to think a Golden State player like Green would rank pretty highly here given their record and you’d be right. He comes in 2nd with 5.2 DWS, right behind DeAndre Jordan with 5.4. Marc Gasol (4.7), Duncan (4.7) and Leonard (4.4) are next best. Curiously, Bogut is absent from the top 20, but that is explainable by his low minutes as compared to the others on this list.
Jordan has been incredible this year. He sits 4th in blocks per game and also in Block %; he leads the league in rebounds, sits 1st in total defensive rebounds as well as Defensive Rebound % and Total Rebound %. His impact on that end of the floor is undeniable and his play translates to easy transition opportunities for the Clippers.
No surprise that the top 5 is made up of the best defensive players from some of the league’s best teams including 2013 DPOY Marc Gasol.
DBPM: Which player has the biggest defensive impact to the box score when on the floor? As outlined in a piece by Sam Amick of USA Today last week, the swing in the Warriors’ point differential when Bogut is on the floor vs. on the bench (22.1) is significantly greater than that of leading MVP candidate Stephen Curry’s (18).
“I don’t really care about the box scores,” Bogut told Amick. “A lot of people who don’t follow us or watch our games look at a box score and say, ‘Oh, four (points) and 10 (rebounds), that’s not a good game,’ but I know the value I’m providing and I think my teammates do too.”
Those assessing the league’s best defensive players also know that value. Bogut leads the league in DBPM with a score of 5.5 points per 100 possessions, ahead of Gobert (5.1), Duncan (4.7), Noel (4.5) and teammate Green (4.0). He impacts the game defensively as much as any big man in the league and that is why he is considered so vital to the Dubs’ title hopes.
Defensive Rebound Percentage: As mentioned earlier, DeAndre Jordan has set the tone with defensive rebounding this season. Not only is he leading the league in total and average defensive boards, but he ranks 1st in defensive rebound percentage. Jordan grabs a whopping 32.4% of available defensive boards, which is nearly 2% points higher than the next best, being DeMarcus Cousins at 30.6%. That’s a huge reason why the Clippers rank in the top 10 in preventing offensive rebounds (10.6 per game) as well as top 10 in FGAs allowed.
Jordan has set career marks in defensive and total rebounds this year on both a per-game and per-36 minute basis. His 829 defensive boards ranks as the 23rd largest total in NBA history.
Rounding out the top 5 in defensive rebound percentage are Andre Drummond (30.1), Omer Asik (28.8) and Pau Gasol (27.6).
Steal Percentage: Think I forgot about the wing defenders? Think again. The leader in steal percentage is none other than Memphis’ Tony Allen who manages to swipe the ball on an estimated 4.1% of opponents’ possessions. Right behind him is Mr. Big Mitts himself, Kawhi Leonard with an estimated 3.7%.
The Grindfather is a perennial All-NBA defensive player, but has never won a DPOY award and isn’t considered a front-runner for the award this year. However, Leonard is and his ability to force turnovers and go the other way is part of what makes him so dangerous as an elite two-way player. Right Stephen Curry?
Block Percentage: Zach Lowe wrote this week that several teams call the large pads used by assistant coaches to simulate shot blockers in shooting drills “Gobert”. He is the most feared shot blocker in the NBA right now and whether you want to call him the “Stifle Tower” or the “French Rejection”, he backs up that reputation with hard data.
Gobert and his go-go-gadget arms lead the league in block percentage by a large margin. Big Rudy blocks a shot on 7% of opponents’ possessions – pretty impressive for a second year player who played sparingly as a rookie and only became a full-time starter after the all-star break. Of course Manute Bol topped 10% on 3 separate occasions, but Gobert has time on his side to match that mark.
In the interim, it’s safe to say that he and his Utah Jazz have earned the respect of the entire league as a defensive force to be reckoned with. Trailing Gobert are Anthony Davis (6.2%), Serge Ibaka (5.8), Jordan (5.4), with Alex Len and Bogut on 5.3%.
Rim Protection: Firstly thanks to Seth Partnow at nyloncalculus.com for his great work in compiling these metrics [2]. Seth calculated several metrics using NBA.com’s SportVu data to analyse rim protection. A detailed explanation can be found here.
I chose 3 of these metrics; Rim FG% Allowed, Contest % and Points Saved per 36 minutes.
Rim FG% Allowed is pretty self-explanatory. It looks at opponents’ FG% at the rim against a certain player. Gobert led the way with an allowed rim FG% of just 39.5%, followed closely by Bogut (40.5%), Ibaka (40.8%), Roy Hibbert (42.3%) and Derrick Favors (43.8%).
Contest % looks at the how frequently a player contests shots at the rim, relative to the number of possible attempts. Bogut contests the highest percentage of shots at 62.2%, with a big gap to the next highest being Hassan Whiteside at 59.6%. Gobert comes in 4th with 55.8%. Amazingly, the NBA’s top shot-blocker, Anthony Davis, contests just 29% of shots at the rim, which indicates he has amazing timing when he does contest shots, but he does not “patrol” the paint given he plays alongside Asik.
Finally, I looked at Points Saved per 36 minutes. Rather than just looking at points saved per game, taking a per-36 minute basis factors in the differences in playing time amongst some of these rim protectors. Bogut again tops the list, saving 3.69 points per-36 minutes, followed by Gobert, saving 3.27 points per-36 minutes. Hibbert (2.46), John Henson (2.15) and Whiteside (2.13) round out the top 5, with Noel coming in 6th at 2.02 points saved per-36 minutes. Anthony Davis did not save any points. In fact he allowed 0.81 points per-36 minutes.
Overall, Bogut leads the way in 2 of these 3 measures and comes in second in the other, indicating he is the best rim protector in the league, even though he finished just 14th in blocks per game. Gobert was next best across the 3 metrics. Anthony Davis and DeAndre Jordan did not factor as elite rim protectors based on these metrics.
What does this all mean?
It’s clear that these metrics paint a very different picture from pure counting stats. There was a lot of chatter earlier in the season about Anthony Davis being a shoe-in for DPOY, but that talk has dissipated faster than a Boston Celtics tank-job. Based on these advanced stats, Davis should not factor in the discussion at all, however given his block totals, I’ve no doubt he will amongst traditionalists.
The other thing to note is there is still a slight bias towards big-man metrics. I struggled to find stats that allowed me to dig deeper into wing defenders’ impacts as was the case with the rim protectors’ metrics. Elite defenders such as Kawhi Leonard, Tony Allen, Jimmy Butler and Chris Paul can be measured only by defensive rating, steals percentage, DWS and DBPM.
Looking at our 9 main contenders, I ranked them in each of the metrics and then tallied the ranks. The player with the lowest total score is theoretically the winner. However, that is on an absolute basis only.
When looking firstly just at the 3 position-agnostic metrics (Def Rtg, DWS and DBPM), the results may surprise you;
The Big Fundamental comes up trumps here, with Draymond Green coming in 2nd ahead of Kawhi Leonard in 3rd.
However, when we expand this to include all metrics, a different winner emerges;
The Stifle Tower raises his arms the highest and takes honours based on ranking each contender in all the metrics.
However, this does not factor in the bias towards big men based on the inclusion of 3 big-men metrics (def reb %, block % and aggregated rim protection) versus just one for wing players (steal %). Making a slight adjustment by reducing the weight of each of the big-men stats (i.e. dividing each by 3) to lessen the impact, yields the following result;
The Verdict: Timmy Duncan gave it a great crack, which is remarkable at age 38 (he’ll actually be 39 next week), while “shooting pads” Gobert will surely be a future winner. Alas, by my count the 2014/15 Defensive Player of the Year is Kawhi Leonard of the San Antonio Spurs.
Over the second half of this season, Leonard’s overall play has been remarkable, but it his defensive ability that has truly defined his impact. We saw this start last year in the NBA Finals when he really troubled LeBron James in Game 3, forcing him into a Finals’ record 7 turnovers.
Leonard has continued to trouble opponents with his quick and huge hands (9.75 inches long, 11.5 inches wide), vast reach (7’3” wingspan) and uncanny ability to make plays. He has the size and strength to body up with larger opponents, can defend four positions and leads the NBA in steals per game and defensive rating.
No wing player has won DPOY in the past decade, but I believe Kawhi Leonard should break that streak when the award is announced next week. To celebrate, he might just let loose with a …. handshake or maybe a “Kawhi Leonard Superhero Sign”, or maybe just a simple Kawhi Five with those giant mitts of his.
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