Oct
08
2020

Stupid Stats: Basketball’s Field Goal Percentage

Welcome to the first installment of Stupid Stats. Stats in sports help fans, players, coaches, scouts, and executives attach a numerical value to a player or team’s performance. Some stats provide a clear representation of a player’s performance. On the other hand, some stats are entirely misused and generally fail to accurately portray a player.

Basketball’s main culprit is field goal percentage.

Field goal percentage is the simplest calculable stat in basketball. One needs two pieces of information to calculate it: field goals made and field goals attempted. It may not be a counting stat like assists or turnovers, but it can be calculated without the fancy formulas of win shares or VORP or other advanced stats.

Why is it stupid?

Calculating a player’s accuracy seems fair enough. It is commonly called “efficiency.” More efficient players have higher field goal percentages, right?

No, not necessarily.

The problem with field goal percentage is that it does not factor in the value of the shot. Hitting 40 percent of two-point shots yields the same percentage as 40 percent of three-point shots, but 40 percent of threes is significantly more valuable to a team. Those 10 two-point shots have a maximum point total of 20 and making 40 percent yields just eight points. On the other hand, those 10 three-pointers have a maximum point total of 30, meaning that making four of 10 (40 percent) is the same as making six of 10 (60 percent) two-point shots.

In essence, 40 percent from the field offers no context to basketball. 40 percent from the field is generally considered to be inefficient or even poor. However, 40 percent from the three-point line is elite, and it makes you one of the best shooters in the NBA.

Case Study:

A member of the Heat shot 43.6 percent from the field in the Eastern Conference Finals. Viewed in the realm of field goal percentage, the player is inefficient. However, only six of those shots were two-point shots. The other 51 were three-point shots where the player connected on 40.8 percent of them: elite production.

The player is Duncan Robinson.

With the immense focus on the three-point shot in the NBA, players are posting lower and lower field goal percentages because a higher percentage of their shots are coming from deeper. The shots are less likely to go in, but they are more valuable.

James Harden:

Harden is practically synonymous with “inefficient.” In his eight seasons with the Rockets, he has hit on 44.3 percent of his field goals. However, field goal percentage fails to acknowledge the absurd amount of threes that Harden takes (and hits at a league-average rate). Over the last three seasons, Harden has taken 1.4 more threes than twos out of his 22.3 total field goal attempts per game. He has connected on 36.3 percent of his threes, a higher mark than the league-average of every season besides 1995-1996 and 2008-2009. By a similar token, he is shooting 53.7 percent on twos in the last three years. Harden is an efficient scorer inside the arc and outside the arc, but his field goal percentage is skewed because he takes so many threes.

Take Michael Jordan as a comparison. He made 52 percent of his two-point shots with the Bulls. Harden has made 51.2 percent of his two-point shots with the Rockets. Over 1,000 shots, Jordan would score about 16 extra points. For three-pointers, Jordan hit 33.2 percent of them with the Bulls. Harden has hit 36.2 percent of his threes with Houston. Over the same 1,000 shots, Harden would have 90 more points than Jordan.

But one look at the field goal percentage would tell an on-looker that Jordan was efficient (for a guard) at 50.5 percent of made field goals. Harden’s 44.3 percent pales in comparison.

This is not to say that Harden is a better scorer than Jordan or vice versa, but using field goal percentage incentivizes easier shots and discourages the three-point shot.

Alternatives:

Effective field goal percentage and true shooting percentage have picked up steam as legitimate stats within the NBA community. Effective field goal percentage accounts for the added value and decreased efficiency of a three-point shot by weighting threes as 1.5 field goals. True shooting includes the value of both three-pointers and free throws. They are harder to calculate than the usual field goal percentage, but they paint a better picture of how efficient a player is. Harden’s effective field goal percentage (52.6 percent with Houston) and true shooting percentage (61.2 percent with Houston) account for the otherworldly production Harden has as a three-point shooter and free-throw shooter.

So, the next time you look at someone’s field goal percentage and think it is “inefficient,” check the player’s two-point field goal percentage, three-point percentage, and effective field goal percentage to get a better grasp as to whether the player is efficient or not.