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Effective Height and Defending the Paint, Part 2


Written by Ian Levy

Our first look at correlations between Effective Height and defending the paint was earlier this week. That post was inspired by another post from Tom Haberstroh at Hardwood Paroxysm comparing Effective Height to team rebounding rates. To recap, Haberstroh created the metric of Effective Height, which is the average height of a team with the heights of respective players weighted by the number of minutes they played. Haberstroh found moderate correlations between eHeight and Total and Offensive Rebound rates. I then took his eHeight numbers and compared them to a few team defensive categories: Block Rate, Opponents At Rim FG%, and the percentage of an opponents field goal attempts which came at the rim. I was surprised to find essentially no correlation between any of those categories and a team’s eHeight.

After seeing those results I wondered if the height contributions of a team’s backcourt might be muddying the correlation data. I then calculated the eHeight of each team using just their frontcourt players. To do this, I used the position designations from Basketball-Reference.  There were a lot of teams I didn’t see much of this season, and I didn’t feel comfortable using my own observations and opinions to assign positions to different players. I am sure some of these position designations are not entirely consistent with a player’s role on his team, but for the sake of consistency I stuck with them.

The first table shows the Frontcourt eHeight compared to Haberstroh’s numbers for each team’s eHeight. I also calculated the difference between the two. The higher the eHeight difference, than the smaller a backcourt the team played with this season. I also included the percentage of a team’s minutes which were played by frontcourt players.

I want to return the frontcourt minute percentage for each team for just a moment. A traditional basketball lineup features 2 forwards and 1 center, or 3 out of the 5 players. Therefore a minute distribution based on a traditional lineup would have exactly 60% of the minutes being played by frontcourt players. Looking at the numbers here it is easy to see the teams ascribe to the small ball movement. Teams like Houston and Orlando, who have true small forwards (Vince Carter and Trevor Ariza) playing a majority of their minutes at shooting guard, stand out as well.

The next table shows my Frontcourt eHeight calculations compared to team rebound rates.

In each case the correlations which much weaker than they were Haberstroh’s team eHeight. I found this to be extremely surprising. Apparently, I have underestimated the rebounding contributions of a team’s backcourt. I also think it’s interesting that you can almost see the influences of individual players. Orlando and San Antonio don’t have particularly big front courts, but they do have Dwight Howard and Dejuan Blair.

The last table compares Frontcourt eHeight to those defensive categories I discussed earlier.

There was an increased correlation with Block Rate, but other than that the correlations were weaker than when using the eHeight of the entire team. Again this would seem to indicate that controlling dribble penetration and challenging shots, have just as much impact as length and height, in defending the paint. I am sure there is much more to this equation than my meager analysis has provided. With an eye towards the NBA Draft it might be wise for teams to focus on the skill set and motor of a player as opposed to falling in love with a physical profile.