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Wednesday, April 04, 2007
The juiced ball
By Tangotiger, 05:29 PM
Excellent analysis from Eric Walker from an old article. He neatly shows the change in run scoring was a sudden spurt in 1992-1994, while the years before and after had their own plateau with a certain variation. Sudden one-year jumps in plateaus are not caused by longterm trends like change in player personnel, player conditioning, etc. And expansion can hardly explain a shift of such magnitude. Parks could cause such a change, if you have enough of them changing so quickly, and you can demonstrate the changes. So what we’re left by is what everybody thought almost 15 years ago: the ball was juiced.
Here’s some data with limited commentary:
pre93 post93
0.285 0.298 BABIP
0.769 0.739 contact
0.292 0.336 XBHH
0.318 0.351 HRXBH
0.059 0.050 speed
0.124 0.096 triples
0.147 0.167 HRK
0.530 0.487 BBK
0.217 0.254 KO
BABIP is hits per ball in play, and we see a big jump.
Contact is 1 minus K+BB-IBB+HBP per PA. So, the hitter/pitcher dynamic changed.
XBHH: extrabase hits per hit. When contacted, a huge jump.
HRXBH: hr per XBH. When contacted hard, a huge jump in HR.
speed: SB-CS per .8*1B+.6*(BB-IBB+HBP). Speed game disappearing as runs go up.
triples: 3b per 2b+3b. Speed disappearing, or turf disappearing, or park fences being closer.
HRK: HR per SO. Huge jump. So, it’s not like they were trying to hit HR more at the expense of more K.
BBK: walks per SO. Huge drop.
KO: K per out. Huge jump.
Remember, these are all, essentially, a jump from 1992 to 1994.