Front-court Defense, Height, and Age

2010 March 5

by durvasa

Does height matter? The answer, to anyone who has followed the Rockets closely this season, has to be yes. The Rockets have utilized the shortest front-court in the league, by a fair margin, this season, as depicted in the chart below:

From above, we see that the relationship between height and team defensive efficiency is not so clear, indicating that there are many other variables (team philosophy, experience) to be considered. The Rockets, as poorly as they’ve defended of late, are actually not too far below league average (though note that the data for the chart above was from before the trade). Still, they have clearly slipped, and the absence of an interior shot-blocking presence has to be the considered the primary reason. But there are others: many new players added to the team is a factor, as well as the Rockets playing more younger players.

Here is another look at this relationship, showing individual front-court players (who’ve played at least 500 minutes ).

“DEF on” is simply the team’s defensive efficiency with each player on the floor, and “DEF On/Off” is the team’s defensive efficiency with the player on the floor minus the efficiency with the player off the floor. Note that the lower either of these metrics are, the “better” the team defense is with that player (presumably, of course this is a bit of a simplification).

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Conclusions? There is a very minimal correlation between increased height in the front-court and better defensive +/- stats, but really the only conclusion one can draw is that (again) height is not a strong indicator of defensive impact. We see that there is actually a somewhat stronger relationship between increased age and defensive impact, which isn’t a surprise.

The problem here is that height is not necessarily a useful indicator of how much “interior presence” a player provides due to his length. What we can do is combine height and shot-blocking prowess into a single metric and see if there is a stronger relationship between that and defensive impact. We will explore this issue further in coming weeks.

Brookaveli

For the charts where players are individually identified by a blue dot, it would be interesting to see what it would look like if you used a different color to denote frontcourt players who were All-Stars this year. Yet another color could be used for last year's NBA All-Defensive team members.
steve-__1

One more thing , How about factoring in "All Star" players. A young tall player may not be as crafty as as an older shorter crafty veteran.
steve-__1

Durvasa

Interesting charts. They pretty much indicate what is generally known- Older tall players decline(Shaq) and average height players are around the middle in the defensive ( Chuckwagon) stats.

Can you do these charts to reflect the season by month. The Rockets being a small quick team seemed to be playing a faster defensive game than they do now as the season has worn on, I would be curious as to how much that decline has been felt stat wise and how the other teams have fared month one as compared to now.

In football time of possession has a great bearing on a teams defensive stats. It ought to translate to basketball also but consider a team that runs verses a team that plays a slower half court offense. However say the team that runs but gets back in transition better than some other team or has a high steal/block factor can you chart something along those lines?

Actually I'm not all that into charts but Morey (and you) puts much stock in it, so back in your cave and don't come out until your finished grinding the data.

Great charts
Easy

That fact that age is a better indicator of defensive effectiveness than height means that the mental aspect is more important than the physical aspect when it comes to defense, at least for interior defense.

Also, Alituro made a good point about weight. And vertical (combining length with leaping ability) is probably a bit more meaningful than simple height.
durvasa

I think the lower left chart (DEF On vs Age) can be explained simply as young teams (which are more likely to use younger front-court players) aren't as good on defense usually. But if age was really that important a factor, I would expected a stronger relationship in the lower-right chart as well. Perhaps I should expand the sample to look at the past 3 or 4 seasons instead of just looking at the current partial season. I may also consider defensive adjusted +/- rather than DEF On and DEF On/Off.
Alituro

Interesting study here Durvasa. I would be anxious to see what kind of conclusion can be drawn from this. One factor I think needs to be taken into account as far as frontcourt defensive effectiveness goes, is weight. Especially if one can assume that the weight/bulk of a player directly corresponds to his strength, as well as having an effect on a player's vertical leap. While shot blocking is the defensive tangible highlight of the frontcourt, the ability to hold one's position in the post or push someone off the block is hard to enumerate through stats, although equally and more often effective.
durvasa

Thanks for reading. Combining height and weight could be interesting, though I have yet to find a good source for player weight. If you know of any, please let me know. I've been playing around with a fairly simple metric I call "intimidation index" which is essentially equal parts height and shot-blocking rate. I think it does a better job of capturing what teams would want as an "interior presence" than simply looking at height, but there are limitations there as well.

BTW, Rahat and I are planning on recording another podcast this weekend. Let us know if there are any particular topics you'd like us to go over.
Alituro

Thanks for asking, the only thing you guys haven't had much input on, because Rahat doesn't want to touch it is Battier's (waning?) effectiveness all around.

One of my main points asking about the weight factor, is that our man (wishfully), Bosh reportedly worked to put on about 15 or so pounds in the off season. Why? He already has a good block rating and height, can jump out of the building. Theoretically the extra weight would hinder his jumping ability a bit. So, how much more important is the ability to push people around and not be pushed vs being tall and being able to block shots? Where does the ideal combo lie? How much more or less intimidating is someone who doesn't give an inch than just a tall moveable stick with some hands way up in the air?
durvasa

Good points. Official weight numbers can be pretty unreliable, and like I said I don't know of a good source for it. But perhaps we can use another stat, like defensive rebounding%, as a proxy for "sturdiness" around the basket. What do you think?
rottendoubt

ESPN has player weight.