Thursday, September 16, 2010

A Note About Points Per Attempt

In my earlier post on offensive metrics, I was excited to present Points Per Attempt (PPA) and quick to praise Brad Schnyders for his offensive performance. I've calmed down a bit since then, and I realized we should probably be looking at this stat in a different way.

What we want to do, I think, is to factor in free throw attempts (properly weighted, of course). Big Ten Wonk introduced this stat points per weighted shot (PPWS). Here's his formula:

PPWS = PTS/(FGA + (0.475 x FTA))

The thinking here is that we don't want to count free throw shooting as a complete bonus. If a player drives to the hoop and gets fouled, he gets two shots (instead of the field goal attempt he was planning on). These two shots should be should (pretty much) be counted as one attempt.

I say pretty much because free throws don't always come in perfect pairs while a player is fouled in the act of shooting. If they did, I think we'd see 0.500 as the multiplier intead of 0.475 in the above formula. Sometimes players make the basket and only get one shot (ideally this one is counted as a pure bonus), and sometimes they shoot one shot after a techincal foul.

So going forward I'm replacing PPA with PPWS. It's been what, five posts, and I'm already backtracking?

Here's the PPWS for the 2009-10 Calvin Knights, with team, opponent, and league averages for reference:


No.PlayerPPWS
30Veltema1.28
20Rodts1.23
10Salo1.17
52Mantel1.07
42Schuster1.06
40Campbell1.04
24Schnyders1.04
22Snikkers1.03
4Powell0.92
14Haverdink0.89
44DeBoer0.86
32Capel0.84
12Waters0.40
50De Young0.00
-Calvin1.10
-Opponents1.03
-MIAA1.03

So maybe Schnyders wasn't as crazy awesome as I originally thought, but we still see that his ability to get to the line helped him out. His eFG% of 0.450 was below the MIAA average of 0.477, but his PPWS of 1.04 was a tick above the 1.03 league average.

The good news for Brad is his PPWS number looks to be very improvable. If he cuts the three point shot from his repertoire and adds a couple of points to his free throw percentage, then he would see a nice jump in this stat.

Then again, there's nothing wrong with being a league average scorer.

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