NBA HD: The Long Sell

With the draft buzz at full tilt, I figured it would be a good time to look at the effect of player length.  Today’s post looks at how a player’s max vertical height (the highest point a player can reach in the air) and how that translated into rebounds at the pro level.  You hear lots about a player’s length and hops at draft time but how does that really affect their actions on the court?

I took the measurements from Draft Express and career total rebound rate for those players that have played at least 50 games in the NBA. There were 241 players in the study.

The correlation between max vertical height and total rebound rate of this sample was .589 which is widely accepted as a moderately strong relationship.  Let’s take a look at it in graphical form.

The best rebounder of this group was Kevin Love who has a 21.2 pct TRR. With a 11’9″ (141 in.) max vertical height, Love’s reach isn’t off the charts for someone who is 6’10” but he has a fantastic knack for collecting the live ball.  For comparison, Nick Young has the same max vertical height and has a rebound percentage of 4.9 pct.

The most disappointing rebounder is Rudy Gay who has a 9.2 pct TRR and can reach over two feet about the rim.  His rebound rate was 6.9 pct lower than what we’d expect given his “freakish length.”

The most impressive rebounder is Reggie Evans who out-rebounded his expected TRR by 12.1 pct.  At 6’9″, Evans reached 137 inches with his max vert height but posted a whopping 20.7 pct TRR.

The correlation between the two variables appears to be pretty strong. But can we make it better? Is there something that predicts rebounding better than the tallest point they can personally reach?

What about regular ol’ head-to-toe height?

Turns out that player height has a stronger relationship with rebounding than the previous matchup.  Specifically, the correlation was .757 which is commonly known as a Harangody-ly strong relationship.  Compare the two distributions. It’s quite apparent that the player height is more compact, less scattered than the max vert height.

So does this mean that we shouldn’t give two Rik Smits about player verticals and length? Yes and no.  Just because Rudy Gay can reach higher than every other player doesn’t mean he can do it in the middle of the paint.  He would need to have plenty of room and run full speed to get to that point.   That only happens on breakaways which rarely happens.  Furthermore, Gay isn’t positioned in the paint because he’s usually guarding a more perimeter-oriented player on the wing.  Ultimately, there’s a lot more to rebounding than how high a player can get; you need to get good positioning, box out, sabotage your opponent’s ability to rise, time your jump, jump instantly, and have the instincts to predict where the ball will end up.  Just to name a few.

Max vert height is sexy but it’s not practical.

Moreover, max vert height can provide benefits elsewhere on the court.  Getting a shot off cleanly and blocking shots — not to mention goaltending– can be boosted by a higher vertical and length.  But we can get into those at a different time.  Also in the future, we can look at confounding variables in this study that might hide some real effects.

Seth Carstens