**Escobar on NBA** wrote:

Here is what I propose: a rubric that takes into account every shot a player makes but weighs those shots according to their value. We start with the notion that a made 3-pointer gives you 3 out of a possible 3 shots. Since a 2-point shot gives you 2 out of 3, we weight it accordingly. Ditto for free throws, only they yield 1 out of 3. What does this mean? Think of it this way: if you added every shot a guy took on a given night and made no distinction between free throws, 2-pointers, and 3-pointers, you’d have an accurate shooting percentage. But . . . what would this number really tell you? A better number would provide some distinctions between 1′s, 2′s, and 3′s. Our new metric does this, by weighing 1′s, 2′s, and 3′s. Here’s the formula:

(FT x (3/9)) + ((FG – 3ptFG) x (6/9)) + (3pt FG)

——————————————————————————— x 100 = Weighted Field Goal %

(FTA x (3/9)) + ((FGA – 3pt FGA) x (6/9) + (3pt FGA)

Congratulations if you’re still with us. It’s been brutal, but we’re almost done. In human terms, all we’re doing there is adding up the number of shots made and dividing that number the number of shots taken, but we’re assigning those shots a weight (1/3, 2/3, or 3/3) based on whether the shot is a free throw, a 2-point field goal, or a 3 point field goal. And notice we are weighing shot attempts as well. This is important, as we will see, because it means our percentage can never exceed 100%. A small victory for common sense. So what does this number tell us? What has this all been for? Let’s plug in J.J. Redick’s numbers to see what we get. On top of shooting 90% from the field and going 5-6 from the 3-point line (83%), Redick also shot 3-4 from the stripe (75%). But these 3 shots from the line are not factored in anywhere in conventional Field Goal Percentage. Conventional Field Goal percentage does not give extra weight to Redick’s 5 made 3-pointers, either. So what we’re after is a number that factors in both 3-point shooting and free-throw shooting.

When we run Redick’s numbers through the WFG% equation, Redick comes out shooting 87% overall. What does this number mean? A couple of things. First of all, when we say Redick shot 90% from the field on 9-10 shooting, we are speaking in terms of conventional field goal percentage. We aren’t, in other words, factoring in free throws. Nor are we weighing three’s more heavily than other shots. And Redick missed a free throw. Our WFG% counts that miss. And our WFG% values 3-point shots (both in makes and attempts) more than other shots. Redick was a perfect 4-4 on 2-point shots. But we don’t weigh those shots as heavily as we weigh his 5 made threes. Redick’s one miss from the field was a 3-point shot, so that miss necessarily counts against him more than a two-point miss would have. There’s probably a lesson in here about how you can’t have it both ways (extra credit for made three’s but no extra penalty for missed three’s), but we leave that for another day.