Spurs improve defensive efficiency by focusing less on defensive rebounding

Kevin Love...

 

I took the 4 factors for offense and defense, plus offensive rating and defensive rating, for season 1974 through 2012. I standardized all the stats for each season (i.e. computed how many standard deviations from the average a team was for each category in each season). I wanted to see how all these stats correlated to eachother. We all know correlation isn't the same thing as causation, but it can give some hints as far as what matters most.

Here's a summary of the results:



First, we see that eFG% correlates much more highly with overall efficiency, on both offense and defense, then rebounding.

<strike>Interestingly, offensive rebounding (ORB%_std) is negatively correlated with offensive efficiency. That is, the tendency is for bad offensive teams overall to put more emphasis on offensive rebounding compared to good offensive teams.</strike> Correction: Misread table. Offensive rebounding is positively correlated with offensive efficiency, but its weak compared to eFG%.

For defense, opponent eFG% was highly correlated with defensive efficiency (r=0.850). Defensive rebounding was also correlated with defensive efficiency, to a greater degree than offensive rebounding and offensive efficiency. It just seems to matter less. Here is graphical view for defensive efficiency against each of the 4 factors on defense:



In short, the Spurs decision to put more emphasize on contesting shots makes sense based on the historical data. Opponent eFG% is the dominant factor for overall defense.

Earlier, I suggested that field goal defense would be negatively correlated with defensive rebounding, although weakly. Putting it another way, opponent eFG% would be negatively correlated with opponent ORB%. Actually, I was wrong, which you can see in the table above. My other statement "Bad teams will tend to be bad at both, good teams will tend to be good at both." won out, I guess. Here's a plot of opponent ORB% versus opponent eFG%:

 

weren't the rockets one of the WORST rebounding teams when they won the first ring?

edit: no they were the best defensive rebounding team sorry

 

Worst offensive rebounding team, if I remember correctly.

 

No, it doesn't.

 

Thanks. So defensive rebounding does contribute to DRtg, and DRtg is the more important number because it includes defensive rebounding.

 

Rockets actually improved quite a bit in defensive efficiency since the beginning of the season. IIRC we ranked somewhere around 26th and now are making stride and becoming somewhat respectful at 17th. Huge progress!

Listed by defensive efficiency ranking.

Rank - Team (PPP) - D Rebound rank (%)
--------------------------------------------
1 - Pacers (0.949) ---- 4 (74.8)
2 - Grizz (0.963) ------ 10 (74.1)
3 - Spurs (0.980 ------ 5 (74.6)
4 - Bulls (0.988) ------ 25 (72.5)
5 - Celtics (0.990) ---- 17 (73.4)
6 - OKC (0.991)------- 19 (73.4)
7 - Wizzards (0.991)-- 7 (74.4)
8 - Clippers (0.992) -- 18 (73.4)
9 - Heat (1.008) ------ 22 (72.7)
10- Hawks (1.011) --- 14 (73.9)
11- Nuggets (1.014)-- 26 (72.2)
12- Bucks (1.014) ---- 28 (71.0)
13- Wolves (1.017) -- 16 (73.8)
14- Nets (1.021) ----- 8 (74.3)
15- Warriors (1.022)- 2 (75.1)

17- Rockets (1.028) - 1 (75.6)
18- Knicks (1.028) -- 5 (74.8)

27- Hornets (1.058) - 3 (74.9)

Interesting stats indeed! Teams with high rebounding % are usually low in defensive efficiency. Maybe there is certain truth to what this article said. Spurs and Pacers are two teams that do well on both.

 

The thing is the Spurs are still a great at getting defensive rebounds. They are sacrificing a few defensive rebounds to contest more shots. Its not a severe dropoff in defensive rebounds. If it was it would not be beneficial in the long run. Its a minor drop off. They are still a top 10 team in defensive rebounds.

Overall, their team defense has improved drastically. It might just be a correlation but there could be some value in this.

 

The more shots you contest the harder it is to get defensive rebounds. Its just a fact.

 

Yes, but the question here is which is more important between field goal defense (i.e. opponent eFG%) and defensive rebounding. And the answer, which agrees I think with conventional wisdom, is the most important thing for a team to do on defense is to contest shots, so field goal defense is the most important factor on defense.

 

So what all you guys are saying is Hakeem sucked at defense?? And that he should just played sound defense and stayed with his man at all times??? Come on!!!

Haha joking

 

The thread on the Raptors SportsVU player tracking. The article says:

Thats crazy to think about. The NBA is already more measurable defensive (and I think just as physical despite old timers assessment) as its ever been. There was already offensive dips year after year until rule changes opened it back up. Its saying the players need to be even MORE active and even MORE closer to the ball action. It'll put the league back to the ugly ball era if everyone cooperates.

THOUGH the NBA schedule is grueling, and players can't give 100% all the time on defense. They'll have to sacrifice on offense, or sacrifice 1 side of the ball.

That kinda validates the Tom Thibodeau / Jeff Van Gundy principles of involving all players in the schemes, multiple players taking away areas of the court. And instead of sending players to crash offensive boards its having the players go back on defense to stop the transition.

And yes even the Shane Battier approach that he's not just on "Kobe Island" 1-on-1 that he's an active team help defender.

So its not just opponents you're guarding but situations and positional areas. Can see how it'd be a bit demanding even in a league known for teams coasting through the reg season.

 

The best half court defenses gives up a bit over 0.8 ppp, whilst the best transition defenses are over 1 ppp, when you're looking at the best ppp and the best drtgs, what you're often looking at is the teams with the best transition defense (indiana is great at both).

 

Yeah thats what it seems to indicate lol. I agree with heypartner on that. Too many pundits and statsmen trying to debunk and making some case. To me its not saying to ignore rebounding. You can't contest the shot and just watch the ball bounce around. And steals and blocks are important. Just there's more to it past that (which we all pretty much know)

I BELIEVE its saying simply being a beast on team rebounds doesnt necessarily mean you're getting all the stops you need (Which was the Spurs issue). I THINK its showing that team HELP defense matters in contesting shots, just as much as the man-to-man. Maybe its better to do all the other things that prevents points and gets you the possession.

Ex: In 5 defensive trips its better to have

A) 1 charge drawn, 1 steal, 1 pass out of bounds, 1 shot clock violation, 1 backcourt violation

then to have

B) 2 rebounds off miss, 2 blocked shot & rebound, and allowing 2 field goals.

In A, there wasnt a single rebound there, and possibly not even a shot attempted. Even if there were shots attempted, they didnt go in.
In B, there's 3 team rebounds and the opponent shooting just 33%. It'll show they're a force on the boards and blocks and allowing a low FG%, but its still allowing more points.

(It maybe makes Hakeem look all that more great seeing all the board work he did, and he still had time for all time blocked shots and top 10 in steals. Not that we didnt know Hakeem had defensive range. He simply covered all the necessary grounds his and everywhere else.)

 

Good stuff Durvasa.

I would bet if you redid this data using only playoff teams you would see some different skews. For instance, offensive rebounding, it's important when two good teams play each other. The best teams maintain floor balance. They always have somebody back. They block out better on the glass, they contest more shots across the board. I think you will find that the tendency is that the better those good teams offensive rebound the better they are....as long as they maintain floor balance.

Bad teams skew data badly. And offensive rebounding is one way this happens. We know they send more guys to the glass and leave themselves open in transition. Our current team is struggling to maintain proper balance in this area. They're fumbling around on the edge of the knife trying to figure out when they can crash and who is going to get back. Hence there are a lot of games where we get chewed up in defensive transition....like a bad team.....but we have so much offense punch with Harden that we make up for a lot of it. As we all know, take Harden off this team and we're down there with the Pelicans and Kings.

To Shroopy: Enjoyed reading your thoughts on defense.

I remember all those games against D'Antoni's Phoenix teams when Van Gundy was coaching. Total contrast in styles. Van Gundy getting our guys to lock up on defense, very elaborate slow offense and D'Antoni's defenses leaving us wide open for layups just so they could increase pace and get into a running game. You remember those games, sometimes they'd run us out and sometimes we'd lock them up, come roaring back from a 20 pt deficit and take them down. However, one thing I remember distinctly..we couldn't beat them often enough. Most of that was due to the fact that we simply did not have enough weapons offensively. It was all TMac and Yao in the half court. And more often than not they wore us down with pace....the same thing we are doing to opponents now.

As I watched Louisville play again last night I couldn't help but salivate about that 94 foot pressing style being played at the NBA level. That is the kind of defense I love. They just choke out the opponent with that constant pressure until the opponent is dead. And I think it is the perfect defensive style to complement and enhance an uptempo offensive game where you run on everything.

I have heard for years it can't be done on the NBA level, too many great athletes in the NBA, the players are too skilled, yada yada yada. I don't believe it. It's a crock of crap. Some innovative coach is going to do it, they're going to commit to running it, they're gonna load up their roster with guys that are quick, fast, and long, they're gonna play 10-11 man rotations and they're gonna go balls to the wall 94 feet defensively for a full 48. When one guy gets winded and needs a blow they're gonna plug in the next guy and continue the next wave of pressure.

Teams in the NBA have 8 seconds to get the ball over half court. Right now, when defenses apply just token pressure in the back court it takes almost the full 8 seconds for guys to get the ball over the line. If they would just start with a 2-man trap and start forcing the opponent to bring more guys back toward the other end to help.....

Why don't teams do this? Because the custom in the NBA is to ratchet down the rotation to 8 guys and play them around 30 minutes a game. They play their best 8. And the reason they do this is whether they want to recognize it or not, they conserve energy on the defensive end. You can't play 8 guys in a pressing style for every defensive possessions and have enough gas left at the end to win a close game. They are operating in this vacuum that the game is going to be close at the end. And they have to still have gas in the tank at the end to win the thing. So, they've got to play the most skilled guys all the minutes and keep the pace at such a level that they can still be effective at the end on all those crappy half-court possessions. No one will commit to 24 seconds of defensive pressure and overplay. Because that style would skew everything. You'd have a bunch of guys averaging 20-25 minutes instead of 8 guys averaging around 30. You wouldn't be playing your superstars as many minutes and that doesn't make sense to them. (Although the truth is almost every NBA team plays their superstars too many minutes now and it results in devastating injuries to the best players in the league.) They're simply not innovative enough on the defensive end.

But some coach at some point is going to do it. And when they do, they're going to set the league on its ear and send a shock wave of change throughout the league. I just wished it were here.

 

I separated the teams into playoff teams and non-playoff teams. Here are the correlation tables for each:



Not much of a difference. Though this isn't isolating games where only good teams play against eachother.

 

and the Knicks were something like the second worst

 

no it isn't. On a spectrum, the hardest way to get defensive rebounds is to allow slam dunks over and over.

if FG% is 100%, you can't get a rebound.

this is why defensive rebounding is as key an indicator as anything else in stats. It is directly related to making the opponent miss their shot.

 

durvasa. Are those stats based on trying to answer a question when the very question might be flawed

 

Which question are you referring to?