APBRmetrics

cherokee_ACB · Joined: 22 Mar 2006 Posts: 157

One quick calculation. If the usage coefficient is 0.25, then the marginal efficiency is roughly 106-0.25*100 = 81, which corresponds to 33% eFG.

Guy · Joined: 02 May 2007 Posts: 128

Eli: Could you say more about why you think weighting lineups by possessions is the better approach? I see the advantage in terms of sample size and reliability. But this will tend to give much more weight to lineups with usage rates close to 1, and minimize impact of very high/low usage lineups. If we only cared about the lineup overall, that would probably be fine. But you're using this to try to understand players, whose usage rates vary far more. So getting a good read on extreme lineups is arguably where you'll get important insights.

It's also interesting that the coefficients are so different depending on how you weight the sample. Suggests the possibility that you have a non-linear relationship here, in which the impact on efficiency grows the more a player departs from his normal usage level (at least for low-usage players, less clear re: high-usage players). That certainly seems plausible. When you have the expanded dataset, you may want to look at non-linear models.

HoopStudies · Posted: Fri Mar 07, 2008 10:47 am Post subject:

Good piece.

Obviously, I come from the bias that this effect must exist. I think your work supports this and illustrates that it is statistically significant. There are some ways to poke small holes in this, but my sense is that the burden of proof goes further towards those saying that this effect doesn't exist.

If you do go to multiple years, you have to consider Ortg/usage being from career, multiyear, or single year data.

As to the magnitude, that ends up being an argument for the linear weights people to deal with. I haven't spent a lot of time trying to figure out the assumed importance those methods make on shot creation or how that relates to the baseline shooting percentage.
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Eli W · Joined: 01 Feb 2005 Posts: 402

Mountain · Joined: 13 Mar 2007 Posts: 1527

Trying to get back to the challenge of a coach I wonder if some data separation could be done to look at relationship between offensive usage/offensive efficiency and defensive efficency in 5 man lineups?

Does that help explain use of low usage and / or efficency lineups better than the offensive data does alone?

Do high defensive efficency lineups within the other 3 groups besides high usage-high efficiency make up for their offensive shortfall on the defensive side of the ball?

Do coaches do better or worse on this net efficiency challenge with lineups used 50+ possessions compared to those below 50?

Would game to game recalculation of this show on average NBA coaches learning the relative strength or weakness of a lineup and either increasing or decreasing use or effectively administering instruction to improve the net results? Or are they guessing in the dark and / or not demonstratig learning or improvement on average? How many coaches/ teams show good results on this?

Strength of opponent defense matters as does strength of defense of your lineup.

Mike G · Posted: Sun Mar 09, 2008 8:02 am Post subject:

Eli W · Joined: 01 Feb 2005 Posts: 402