(The Non-Negative Value of Negative Spacing)
There's a well known bias in academic publishing that favors papers that find statistically significant results over any study that doesn't. That is unfortunate, because sometimes it is as important to find evidence to rule out relationships or causation as to find evidence to support them.
Of course, blog posts don't go through a committee or reviewers; but there is still a natural bias I think to report research that finds significant relationships. This isn't going to be one of those posts.
OK, throat clearing over, I have been doing a whole series of posts on shot location in the NBA here and at Hickory-High. The last one looked at the independent value of of having 'Stretch' shooters on the floor in addition to the improved efficiency of the three point shot. In that study I found that having at least two Stretch shooters on the floor appeared to improve a line up's offensive efficiency as measured by points per 100 possessions (ORTG), but adding an additional Stretch shooter did not aid offensive efficiency.
In my shot location Cluster Analysis series I found three groups of Big players; players who shot almost exclusively from arms reach of the basket, stretch Bigs that shot three point shots and Hybrids that had a mid range game.
This is how the shot selection and statistics looked for each type:
| AVG Att at the Rim |
% Att at 3-9 ft |
% Att at Mid Range (10-15) | % Att at Long Two(16-23) | % Att of Three Pointer | ||
| At the Rim Big | 67.31% | 21.24% | 3.58% | 7.62% | 0.36% | |
| Hybrid Big | 40.31% | 16.47% | 10.94% | 29.88% | 1.96% | |
| Stretch Big | 26.10% | 9.32% | 5.83% | 19.36% | 38.91% |
The 'At the Rim' shooters displayed almost no spacing value, and the majority of Bigs fell into the middle category.
In terms of interior spacing, there has also been a good deal of discussion about the viability of line ups with two bigs with limited jumps shots, such as Dwight Howard and Omer Asik in Houston. Both scored as 'At the Rim' shooters, and have displayed limited range on their jump shots.
Given that, I decided to add to the spacing analysis with some negative space analysis of Bigs. I coded every 'At the Rim' big as a negative -1, then added all of the negatives together, finding this distribution for Line Up combos over the last two years:
.
| Statistics | |||||
| RimBig | Count | Offensive Rtg | TmTOV | AST Ratio | Net Rtg |
| 2 Negative Spacers | 8 | 103.04 | 16.33% | 17.59 | 3.53 |
| 1 Negative Spacer | 50 | 104.42 | 15.62% | 17.85 | 2.72 |
| No Negative Spacer | 36 | 104.76 | 14.50% | 18.95 | 3.51 |
There were only eight line ups with 2 Negative Spacing Bigs that played over 200 minutes together in the last two years, indicating coaches certainly believe in interior spacing's value.
In the examples found there was little absolute degradation in offensive rating for the handful of line ups the featured 2 Negative Spacers without a distance or mid-range game. In fact the Net offense rating minus defense rating of the 2 Negative Spacers line ups were better than the 1 Negative Spacer line ups and virtually identical to the no Negative spacer line ups.
Looking at the difference between expected offensive rating ORTG based on the average of players in the line up and the actual ORTG achieved, there was also little evidence of a negative spacing effect. There was no statistically significant effect from having negative spacing in the front court in any filter of minutes played together.
In fact one of the line ups that worked well last year and continues this year, is the starting Toronto line up with Jonas Valanciunas and Amir Johnson, who no one comments on because they play in Canada. That line up had an average ORTG but a very good defensive rating for a Net of +12.9 per 100 possessions over 354 minutes last year.
Returning to Dwight Howard and Omer Asik playing together, this study found no negative effect of playing two Negative Spacers on the floor together. All that suggesst that Asik/Howard could work together. However, even without an independent effect from negative spacing bigs, Howard and Asik had the lowest ORTG of the Rocket's current starting line up last year, both being below the league average.
And to date it hasn't worked that well in Houston. Part of the issue is that Asik just isn't playing well so far, his eFG% through six games is down ten points to 45.5% and his turn over percentage is up to 28.8% from 18.8% last year. But neither can be blamed on Howard, as Asik's eFG% is higher and TOV% is marginally lower when on the court with Howard according to NBAWowy.
It also appears that having Asik and Howard on the court is clogging the lanes for their teammates. Harden, Parsons and Lin are all taking a lower percentage of their shot attempts at the rim when the Asik/Howard tandem is on the court than when it is not, again via NBAWowy.
| Player | % of Shots 0-3 feet WITH Asik/Howard Combo |
% of Shots 0-3 feet WITHOUT Asik/Howard Combo |
| James Harden | 20.8 | 33% |
| Chandler Parsons | 34.6 | 60% |
| Jeremy Lin | 33.3 | 39% |
In fact, so far the team as a whole has taken a higher percentage of their shots inside three feet when the Asik/Howard combo is not on the court than when they are.
Part of the problem in addition to opponents sagging off of them may be contained in the high turnover and low assist numbers for both Howard and Asik, neither of whom are particularly good interior passers, and that's generous for Asik.
But the evidence I found suggests that line ups with two space clogging bigs can work, whether Asik and Howard will work is too early to tell.
(Note light editing added 11/9/13 for clarity)
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