The Value of Spacing

Offense and defense in the NBA are a battle over space, with the defense seeking to devour it as quickly as the offense can create it. Defenses try to create bottlenecks in front of the ball while having defenders close enough to all dangerous shooters to challenge them should the ball end up in their hands. The offense is trying to force defenders far enough apart that they can move freely around the floor, probing and prodding for the best open look they can get. This battle for space is one that the Toronto Raptors seem to be consistently losing on the offensive end, especially against good defensive teams.

It’s tough to quantify the value of open space but Stephen Shea, PHD has made an attempt in a chapter of his excellent book Basketball Analytics: Spatial Tracking, using SPORTVU data to measure the actual area that a defense occupies on the floor and how the personnel used by the offense impacts it. He came up with a few statistics for this purpose:

  • CHAD(Convex Hull Area of the Defense): if you were to take an elastic band and stretch it around every defender at any given point in time what would the area inside the elastic band be? That’s the CHAD.
  • DDA(defense’s distance from average): the average distance of a defensive player from the centre of the CHAD
  • ODA(offense’s distance from average): the average distance an offensive player is from the center of the offense

Looking at the 2013 Miami Heat during their series against the Spurs what he found was almost exactly what you would expect but it’s still interesting to see it quantified, particularly with the players that Miami had on the roster because it contains some valuable information for the Raptors. First, he found that there was a strong correlation between the DDA, CHAD and the amount of shooters on the floor – going from 2 to 3 shooters increased DDA by 3 inches and from 3 to 4 by an additional 6 inches, with those seemingly small increases leading to a 14% increase in CHAD when going from 2 to 3 shooters and an additional 24% increase when adding a 4th shooter. He also found that when the team replaced the superior overall player but nonshooter Dwyane Wade with on-the-verge-of-retirement Ray Allen that alone was enough to increase DDA by 14 inches even though Wade’s ODA was actually higher than Allen’s. Granted, Allen is a uniquely dangerous shooter but even if that increase is halved by putting a lesser shooter on the floor it still presents significant advantages for the offense.

Shea also found that there was a strong correlation between the size of the CHAD and the amount of points given up, with each additional shooter significantly increasing the offensive points per possession: 0.77 ppp with 2 shooters, 1.39 with 3 shooters and 1.77 with 4. Some of this is obviously due to the personnel involved but it’s reasonable to assume that while the difference wouldn’t be as pronounced with shooters who aren’t quite as good as Allen or finishers as good as Lebron James there would still be a significant difference. That extra 9 inches of DDA can mean the difference between a block and a charge or between a help defender getting in front of a ball handler to reroute or merely being able to swipe at the ball as he drives by. It gives a post player that extra split second to make the correct read as the double comes from a little bit further. It’s more space for defensive big men to cover in mismatches or in pick and roll situations and it can be the difference between a completed pass and a deflection or a deflection and a steal.

Why is this important for the Raptors?

It’s been long enough that we can say with a fair amount of certainty that DeMar DeRozan will never be a threat from the perimeter. He peaked as an average midrange shooter and is currently significantly below average there this season, with his mediocre scoring efficiency currently being buoyed by his free throw rate. As Shea’s quick study of the 2013 Finals shows that can be said to be imposing limits on how effective the offense can be, as the only way to get four shooters on the floor with DeRozan is to have quality shooting at both power forward and center, positions where shooting is at a premium. It also shows that downgrading in overall player ability but bringing in a skillset that helps increase spacing can actually be a plus move for a team.

When you look at lineup data from last years Raptors team, lineups with more than 30 minutes played and two shooters(defined as players who took more than 1 three pointer per game and shot better than the break-even point of 33%) posted an average offensive rating of 101.2 over 10 occurrences while lineups with three shooters posted an average offensive rating of 114.2 over 17 occurrences. There were only 5 occurrences of lineups with 4 shooters but those posted an offensive rating of 111.8. Those of you who wonder why Terrence Ross continues to get minutes and why Alan Anderson used to play so much despite them both being objectively bad players or why James Johnson doesn’t get more burn, you have your answer.

This limits the lineup options available to the Raptors, who essentially can’t play DeRozan with young centers Jonas Valanciunas and Bebe Nogueira or enigmatic forward James Johnson unless accompanied by three shooters, which means that Luis Scola needs to keep his three point shooting up while Terrence Ross and Patrick Patterson start hitting consistently to keep the Raptors offense with DeRozan viable against a disciplined defense. It also means that the Raptors don’t have a lot of options against elite defensive teams who manage to gobble up space effectively, which is part of why the Raptors offensive rating dropped from 108.1 on the season to 101.2 against top 10 defensive teams last year. The lack of open space to move against those defensive teams also explains why the slashing DeRozan’s TS% dropped from 51% to 47.5% – not what you want to see from your highest usage player when the league average over the last few seasons has been between 53-54%. We saw a great indicator of the impact that can have during the Raptors recent game against the Golden State Warriors, with the Warriors able to cheat off of DeRozan when he was on the weakside to make the Raptors pick and roll attempts more difficult than they would otherwise be with DeRozan’s man coming close to ignoring him entirely at times and being right on the edge of the paint at others. Here DeRozan is out of the frame in the weakside corner, and nobody on the Warriors seems to care:


Compare that to this pick and roll with DeRozan on the bench, the play is much closer to the 2 on 2 play the Raptors would like it to be with one defender in the paint instead of three:


This isn’t to say that DeRozan necessarily has to go, just that his particular skillset complicates things for the Raptors and can be said to contribute to the Raptors struggles with taking that next step and being able to consistently hang with the NBA’s elite. The Raptors haven’t really taken a significant step forward since trading Rudy Gay two years ago, they’ve just been a middle of the pack team for different reasons each year and are currently on pace for more of the same. As the team contemplates what direction they’d like to go with DeRozan in the last year of his contract with multiple years already committed to the much younger and much more efficient Valanciunas they’d be wise to consider the positive impact that additional shooters can have on the teams offensive performance.

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