01-01-2022, 10:59 AM
(01-01-2022, 10:40 AM)mavsluvr Wrote: Don't know if anyone has read Seth Partnow's new book, The Mid-Range Theory. He is a stats guy and formerly worked in the Bucks front office. The book is an explanation of basketball metrics and how they are used by NBA teams.
He spends a fair amount of time discussing the various +/- stats, and how front offices use them. A few points relevant to the discussion --
1. Raw +/- figures are far too noisy to provide a basis for any meaningful analysis, even based on an entire season of data. Even with multiple seasons of data. Teams usually have proprietary figures of their own, with numerous adjustments to try to filter out some of the noise. Even with numerous adjustments, it is a noisy stat, and is never used by itself for player evaluation purposes.
2. On-off +/- can be a useful starting point, but it's very easily over-interpreted, and what you can glean from it is wholly dependent on context. For example, one of the team's starters might spend a stint or two every game anchoring an otherwise weak lineup. In such a case, the team's scoring margin could very easily be higher when the starter is off the court, due to the weak lineup dragging the starter's +/- down. Jumping to the conclusion that the team plays better without the starter, based on the on-off stat, would not be justified. Similarly, being on or off the floor in blowouts tends to affect cumulative +/- disproportionately, and it is not unusual for garbage time lineups to look much better or worse than the scoring margin of the team as a whole.
3. Adjusted +/- stats must be considered with the known limitation that they rank zero in "explainability." That is, they tell you something about what happened on the court, but tell you absolutely nothing about why it happened. You have to do a contextual dive to learn anything at all from these stats. For example, which teammates were on the floor at the time being measured, which opponents were on the floor at the time being measured, what were the circumstances in the game at that point (clutch, garbage time, etc.) and much more.
4. In evaluating the usefulness of stats for various purposes, one must be conscious that they should pass the smell test. If particular stats lead you to a conclusion that seems very counterintuitive, maybe you've discovered a surprising nugget, or maybe your stat isn't really telling you what you think it is.
5. By far the most important stat is shown on the scoreboard, and NBA statisticians are aware that achieving wins is their North Star, not achieving some other statistical outcome.
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It's an interesting book, for people interested in that type of thing, as it provides an inside look.
Anyway, I think it points in the direction of a common-sense analysis.
Once called the eye-test.
