The explanation of how I calculate Shot Quality is below the chart.
Shot quality analyzes a player’s shot selection given his shooting performance. A shot which is a good/bad shot for most players may not be for every player. As an example: A wide-open 14 foot jumper is a pretty good shot; the league average performance on this shot is high. It is not a good shot for Marcus Smart to take. Conversely, a 28 foot jumper is a bad shot in general, but palatable for Steph Curry because he makes them at a relatively good clip. Shot quality is similar to shot selection except that it calculates the value for player’s shots given the player’s own shooting performance, and that it compares the player’s performance with league average performance on that shot, for each shot. In simpler terms. Shot quality takes every shot and asks: How well does this player do on this type of shots? How much better or worse is he than league average on these shots? How many of this type of shot did he take?
A player’s total shot quality rating is a percentage a little above or below 100; it expresses what percent of league average value the player’s shot selection represents, given his shooting ability relative to league average. A player with a shot quality of 105 is 5% better than league average at shot selection when we compare his performance shot-by-shot against league average performance on those shots. Put another way, replacing this player with an exactly league average shooter and expecting him to fill the exact same role would cost the team 4.76% of the original player’s points (percent change = (((100-105)/105)*100), which equals -4.76%). Unlike shot selection, I run the data for shot quality for time remaining on the shot clock as well as range, area, and nearest defender. This tends to depress the evaluation of players who shoot early in the shot clock, even if they tend to make the shots.