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P1 of Basketball Analytics with Jackson (Scoring Efficiency)

About a year ago I came up with a story. A (sells his lemonade for $1.00) and B (sells lemonade for $1.50) start lemonade stands. Let’s look at them. A and B set up right next to each other where 100 customers will see each of them. A sells 51 cups of lemonade while B only sells 34 cups. 

A: 50% “Conversion Rate”, $0.50 per customer 

B: 34% “Conversion Rate”, $0.51 per customer 

Let us make this a bit more complex and add in tips. We’ll call them tip attempts where the seller can receive $0.50, and every 2.25 tip attempts is worth one customer walking by. C (sells lemonade for $1.00) decides he wants to compete and makes his own stand. C gets 45 tip attempts which is equivalent to the chance of selling to 20 customers. He successfully gets 36 of these tips. With the rest of his 80 customers, he sells 40 cups of lemonade.

A: 50% “Conversion Rate”, $0.50 per customer 

B: 34% “Conversion Rate”, $0.51 per customer 

C: 50% “Conversion Rate”, 80% “Tip Attempt Rate”, $0.58 per customer

“Conversion Rate ” is the same as FG%, and per customer is the idea of TS% and EFG%. 33.33% from 3 is just about the same as 50.00% from 2. Top mid-range shooters will shoot 55% if they’re elite while that is the same as 36.67% from 3, which is only a little bit above average. FG% is simply how often a shot will go in with no context as to how much that shot is worth. EFG% ((FGM + 3PM x 0.5)/FGA) makes 3PM 1.5x more valuable than a 2PM. TS% (PTS/(2(FGA + FTA x 0.44)) gives a value to a FTA and now you have a complete formula. Guys who score the most points per possession give us the highest chance of winning! Getting FTA, in general, is very efficient so drawing fouls leads to good offense. James Harden, from 2014-2015 to 2019-2020, had a 44.2 FG%, 36.1 3P%, and 52.9 EFG%. In all honesty, these seem similar to the league average, but once we dig a bit deeper we see how far from the truth this is. Harden’s TS% would constantly be 11-13% (TS+ ranged from 111-113) higher than the league average. Harden represented C in the lemonade example. On the opposite end, we see Andre Drummond. Throughout the same time span, he had a 54.0 FG% (FG+ ranged from 115-116) which is well above league average yet only has a 54.0 TS% (TS+ ranged from 92-100) which is below league average. Drummond is meant to represent A. Here is another example. 

Player X: 44.2 FG%, 36.8 3P%, 87.9 FT%

Player Y: 50.5 FG%, 42.6 3P%, 92.8 FT%

Player Z: 47.2 FG%, 43.7 3P%, 91.6 FT%

How would you rank these players on pure efficiency? Y, Z, X? The right answer is Z (64.1 TS%), X (61.6 TS%), and Y (61.4 TS%). Just a small difference but FG% is very misleading if it is used to assess scoring efficiency, especially when comparing players with different shot diets. 

STATS:

EFG: Points per possession on field goal attempts. ((Field Goals Made + (0.5)3 Point Makes)/(Field Goal Attempts)

TS: Attempts to measure scoring efficiency as a whole, takes into account how much each shot is worth, and gives a possession value to a free throw. ((PTS)/(2 (FGA x (0.44)FTA)))

TS+: Percent above league average TS%. 100(TS%/League Average TS%)

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