TS% or eFG%?

Kevin C. Cox, Andrew D. Bernstein/NBAE via Getty Images

While basketball can be described best as a qualitative game rather than a quantitative one when it come to statistics, advanced statistics and analytics certainly have a place when assessing a player. Pioneers like John Hollinger and Daryl Morey have brought statistics past the basic box score stats to light. Things we commonly use today like player efficiency rating, value over replacement player, and win shares have all stemmed from the analytics movement that has taken the NBA by storm. When looking at shooting efficiency specifically, a trained basketball mind will typically look past the normal field goal percentage and three point percentage and towards stats like true shooting percentage and effective field goal percentage. Looking at the leaders for both true shooting percentage and effective field goal percentage this past season brings up two extremely different players: Kyle Korver at 70% true shooting and DeAndre Jordan at an effective field goal percentage of 71%. Obviously, the two stats weigh the percentages available on different levels, so we're going to take a deeper look into what makes up these equations and what kind of players the equations lean towards.

True shooting percentage, abbreviated as TS%, is a stat developed by APBRmetrics to measure how efficiently a player shoots the ball. The equation itself isn't actually too complex. It looks like this:


PTS stands for points, FGA stands for field goals attempted, and FTA stands for free throws attempted. The 2 essentially makes the end product look like a percentage, as otherwise the number looks more like points per field goals attempted. The 0.44 is more subjective than anything, as that is what APBRmetrics valued a free throw attempt compared to a normal field goal attempt.

On the other side of things, there is effective field goal percentage, often abbreviated as eFG%. eFG% looks at field goal makes instead of points per attempt, and the equation looks as follows:


In this case, FG stands for field goals made, and 3P stands for 3 point field goal made. The 0.5 in the equation accounts for the fact that 3 pointers are worth 50% more than 2 pointers, and thus must be weighted fairly. Where TS% and eFG% differ is in what they take into account when calculating their values. eFG% looks at both field goals made and attempted as well as putting 3 pointers into their own category, whereas TS% looks at points scored and attempts, seperating free throws attempted from the rest. So why does Kyle Korver lead the league in TS% if eFG% seems to favor shooters more? Why does DeAndre Jordan lead the league in eFG% if he doesn't shoot threes? Well, we know that about 75% of Korver's attempts this year were 3 pointers, which he converted at an extraordinary 50% clip. Keeping in mind that TS% is essentially points per attempt/2, the sheer volume in which Korver hits threes combined with the fact that Korver converted them extremely well puts Korver at the top. Looking past Korver on the league leaders, we see this:

Looking at the list, we see two kinds of players: efficient 3 point shooters (Korver, Curry, Morrow) and at-the-rim style big men (Chandler, Jordan, Gobert). The gap between Korver and Chandler is a miniscule 0.02%, telling us that Korver and Chandler scored approximately 1.4 points per attempt. We also see DeAndre Jordan close by, our league leader in eFG%. When we look at the top 20 in eFG%, we see similar results:

Compared to the other list, the gap between 1 and 2 is much larger, about 1.2%. The players we see on this list are much different than the TS% list. While some players like Jordan, Valanciunas and Curry make a second appearance, the kinds of players we see on the eFG% list is much more varied, with multi-faceted players like LeBron and Paul making the list. From this list we can see that while eFG% favors elite 3 point shooters, players who score from all around the floor make the cut due to their high field goal percentages elsewhere (i.e. LeBron in the paint, Paul from mid-range).

Even though TS% and eFG% serve to replace basic stats like FG%, the two tell us much different stories. If you are looking for a stat that tells you how efficiently a player scores based purely on how many attempts they take, you should mainly look at TS%. On the other hand, if you want a stat that is more fair than straight-up FG%, you should be using eFG%. Just a heads up: This past season, DeAndre Jordan placed 4th all time in eFG% amongst players playing more than 50 games. Who's in front of him? NBA legends Chris Wilcox, Wilt Chamberlain, and Ryan Hollins, of course.

Credits: Getty Images, basketball-reference.com, en.wikipedia.org