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October 31, 2002 - Mikael
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Interesting. Even though our group of stars were 49% above league average for 3 straight years, their next year averaged 42%. What this implies is that these players were probably slightly lucky for three straight years, and that their true talent level is actually 42% above average. These players retained 86% of their value, meaning that they regressed 14% towards the mean.
It seems likely to me that this sample is heavily weighted with players reaching the end of their peak. A few Hank Aarons will have more than three years at 150% of league average, but most players will reach that peak for a few seasons and then decline. I think you may have found an aging trend - a real reduction in skill - not a regression.
Baseball Prospectus - : Evaluating Defense (March 1, 2004)
Discussion ThreadPosted 1:22 p.m.,
March 2, 2004
(#21) -
Mikael
I posted this over on Clutch Hits, before Darren directed me here.
I hate to be That Guy ripping on Prospectus. I like them and what they do.
But I have mad ish with the "BP Basics" article today on defense. It starts well, with the classic argument against errors and F%, against judgments based on anecdotes. But in discussing the proposed solutions to these problems, James Click lauds Davenport's Fielding Runs as the latest advance over Range Factor, with no mention of similar systems like Win Shares or Context-Adjusted Defense or others. It makes only oblique reference to PBP stats, primarily as proprietary metrics owned by teams. MGL's and Pinto's and everyone else's work is ignored.
I understand that they are a corporation with corporate goals, and they've decided that mentioning extra-BP research harms their pursuit of those goals. But right now, they're publishing a piece whose stated goal is to help readers in "understanding the game better," while willfully ignoring most of the issue for purely profit-based reasons. I think that's really, really lame.
Lame.