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Q. I'm not a geek; I just like baseball. What is "Pythag"?
A. Bill James noticed, in like 1984, that if you ratio a team's runs scored to runs allowed, you can come up with an "expected winning percentage." To James, the algebra of it sort of looked like geometry's Pythagorean Theorem.
Then everybody else tried to claim rights to the formula by making little tweaks to it. In this section, (whoever wrote) the Wikipedia (entry) argues ferociously that the original formula Just. Wasn't. Good. Enough. For Real. Scientists, so you should get the current "expected" standings from them.
I can't imagine how James feels, to have 100+ major discoveries co-opted by people who took his INSIGHTS and made them a teeny bit more precise, and then ... sigh. Voros McCracken built a baseball life around ONE James-level insight, the idea of BABIP. Imagine if everybody tweaked that, and then forgot about McCracken. Were the Wright Brothers more important, or the average Boeing engineer?
But hey. James has been named one of the WORLD's 100 most influential people (?!?!), is inside baseball, etc., so it's not like he didn't reap benefits. :- )
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Q. Wow. He invented Pythag in 1984? That's like before computers.
A. I dunno when it really was. Many of James' discoveries did come in the 1980's, even 1970's.
Actually, much of James' early revolution occurred before computers meant anything to the regular person. "Sabermetrics" was often defined by sportswriters as "the computerized use of baseball statistics." Personal computers were kind of cutting-edge in the 1980's.
(James himself says "I can't imagine a worse definition" and defines his invention --sabermetrics -- as "the search for objective knowledge about baseball." In his zeal for that, he'll listen to anything as evidence. Including public perception, sportwriter HOF balloting, advance scouting reports, etc.
He "gets it," that we are not world-class scientists here, writing for the Journal of the American Medical Association. We're just fans, trying to "see" baseball better. We're surprisingly good at it, but the fact that we use algebra --- > doesn't make us scientists.)