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Sunday, August 17, 2003
turn and face the strange ch-ch-changes
i know you guys like it when i change pow, so i'm doing it again.
you know how current pow includes (tb-h)/(ab-so) as its central component? that puts hr, 3b, and 2b in a 3 to 2 to 1 ratio. what i got to thinkin was, if pow is supposed to measure how hard one hits the ball, it doesn't seem like home runs should be 3 times as meaningful as doubles. 3 to 2 seems better, because a home run is just a double plus a little extra.
i ran a bunch of correlations and regressions, and 3-2-2 is indeed better. 1-1-1 also works well.
it makes sense. there's no need to count extra for home runs, because a home run hitter already has more extra-base hits. and usually when someone's home runs are down, their doubles are up. they're not hitting it any less hard, it's just that some of those home runs hit the wall.
remember, we're not trying to measure value, we're trying to measure power. the new system works with smaller sample sizes too, because hr+2b is much less variable than hr or 2b alone. it also mitigates park effects.
we'll use 3-2-2 because it works for all kinds of hitters. but 1-1-1 is better for tiny sample sizes. and it has a nice look:
3-2-1 pow = .273 + .212*(3*hr+2*3b+2*2b)/(ab-k)
1-1-1 pow = .273 + (1/2)*(xbh)/(ab-so)
xbh is extra-base hits.
.330 is still the baseline. top power hitters will come down a little. weaklings will come up. con*pow is still a predictor for average. it's better, now, in the extremes.
in the last article we mentioned that shawn green has been unlucky with extra-base hits. look how much more consistent his pow's are:
pow old new
1993 .273 .273
1994 .284 .290
1995 .350 .351
1996 .331 .336
1997 .340 .337
1998 .358 .351
1999 .371 .365
2000 .345 .346
2001 .377 .363
2002 .369 .359
2003 .332 .341
javy lopez and jim thome:
javy jim
old new old new
1994 .336 .329 .372 .364
1995 .336 .328 .365 .360
1996 .336 .330 .392 .378
1997 .358 .354 .391 .376
1998 .361 .350 .395 .388
1999 .347 .346 .388 .376
2000 .341 .334 .381 .371
2001 .328 .324 .419 .398
2002 .321 .320 .423 .396
2003 .399 .379 .389 .377
haiku:
a baseball player's
career rises like a wave
to a gentle break
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