(And The Shooting Competence Curve)
Last October I unveiled my Scoring Versatility Index at Hickory High. The idea at the time was to create an index that graded a player's efficiency scoring in a variety of ways including from different spots on the court and from the line, with the theory that a player efficient from more locations would be harder to guard.
The immediate problem that I found was that as one carves up the court into smaller pieces one creates more data sets with smaller sample sizes, and the less reliable data. It is a problem, as I have noted, with the shot chart era in general. Carving up the court into pretty pictures can sometimes give us pretty unreliable impressions. Looking to account for this has been an interesting challenge and lead me to a few somewhat unexpected directions.
Players with only a few shots from any zone will have averages unreflective of their 'true' talent level, and, in fact, with three point shots the inherent high variability it takes a fairly large number of shots to determine true talent with any confidence.
Statistics and a couple of assumptions can help us out here. Over a given period players will shoot above or below their 'true' ability based solely on random variance (compounded, perhaps, by opponent variation, injuries, confidence levels and so on). It's a tried and true assumption that after these streaks, over the longer term the player's shooting percentage will revert or regress toward their 'true' average, with reversion taking longer with a higher variability.
That leaves open the question of what the player's true shooting ability.
My assumption also was that a player that rarely takes a three point shot is likely to be a 'replacement' level three point shooter rather than an average one. That's convenient for estimating the Versatility Index as crediting every player with average percentages with few if any shots would not help in measuring difference in scoring versatility. When I looked at the data is also happened to be true.
Using the NBA.com shot zone data I charted each of the NBA's five shot zones with each player's shooting percentage against the number of shots taken in that zone. (The zones are the restricted area, paint outside of the circle, mid-range, corner three and above the break three). For the three jump shooting zones in the mid range and the threes the pattern was pronounced, players who shoot more mid range jumpers, for example, make them at a higher rate.
The number of attempts from the mid range conveys two pieces of information, the amount of time the player is on the court and the degree of comfort the player and his coach have in him shooting in the mid range, ie whether that is one his spots. Contrary to some opinions coaches have some idea who their better players are and players have some idea where they shoot better. The same is true of corner and above the break three point shots.
Curses and Blessings
The problem, for mid range shooters, is that even for good mid-range shooters the shot isn't terribly efficient. That can be seen in the image below along with the increasing expected competence with more attempts via a logarithmic trend line.
Only the most efficient mid range shooters like Chris Bosh and Dirk Nowitzki approach league average efficiency as measured by eFG% (the dotted line) from mid-range. Players like Carmelo Anthony, DeMar DeRozen and LaMarcus Aldridge last year were fairly good (and liberal) with a not good shot.
Via Ian Levy's work on Xpps, the average point per shot for a mid-range attempt is .793, or an eFG% of 39.6%. The competence curve on mid range shots last year indicates that players who attempted fifty to sixty mid-range shots were more likely to average near 36%, while players with just over 150 attempts the expected competence is closer to league average and high volume mid-range shooters the curve rises to only 42% to 43%.
In contrast, most of the more prolific shooters of the above the break on the three hit for above average efficiency. And we also see the same increasing competence curve, leaving players on the right side of the image taking a allot of an efficient shot and being pretty good at it.
All of the most prolific shooters of above the break threes hit is with above league average efficiency, with only Kobe Bryant and Goran Dragic, last year, hanging around league average on those shots. The curve indicates that a player taking 50 above the break threes as an expected eFG% of about 44% on those shots, higher than the more prolific and skilled mid range shooters. The players higher on the competence curve shooting above the break threes show an expected eFG% of aproximately 58%.
To be clear, the train of causation here is primarily that players are taking the shots they are more comfortable, and skilled at, more often. And that those shots are more likely to be within the flow of the offense than Chris Anderson's random above the break heaves or DeAndre Jordan's stray fifteen footer.
On the mid range shots, hitting a higher percentage is certainly better than shooting many and hitting fewer. In addition, part of the impetus for the Scoring Versatiliy Index was the idea that being efficient from more spots on the court puts more pressure on the defense than a specialist like Kyle Korver or DeAndre Jordan.
Currently two of the NBA's most efficient offenses, the Houston Rockets and Portland Trailblazers, featue very different ideas about spacing with the Rockets focusing entirely on three point shots and the Blazers featuring a mix that includes Aldridge's mid range game in addition to highly efficient three point shooting. So clearly an effective mid range game can be a part of a larger efficient scheme, if only to open the floor to other, better shots.