Post on 17-Jan-2017
transcript
SABERSEMINAR 2015 @BLABABOUTBALL
How do parks really affect outcomes?
Park factors are great!◦ Calculated as averages, and should be applied to averages◦ E.g. when calculating wRC+ you adjust baseline up or down based on home park, not the player
But what happens at the extremes?◦ Do parks really affect all players equally? Probably not.
Difficult to analyze◦ Measuring a park effect requires large samples◦ Most parks are fairly neutral◦ Extreme parks tend to get altered
SABERSEMINAR 2015 @BLABABOUTBALL
(Mostly) unchanged since 1940
At least one extreme park effect◦ 30%+ impact on doubles, >25% for both LHH and RHH
Fenway fits the bill on both fronts
SABERSEMINAR 2015 @BLABABOUTBALL
Found a park… how do we examine it?
Split hitters into extreme groups and see if they’re affected differently
To do that:◦ Calculate 2B/PA deltas for visitors to Fenway vs. other road games, 1956-2014◦ Group hitters into quartiles each year by projected 2B/PA rate (using Marcel)◦ Find weighted averages by quartile and hand
And the results say…
SABERSEMINAR 2015 @BLABABOUTBALL
For RHH, Fenway doesn’t discriminate
1st Quartile 2nd Quartile 3rd Quartile 4th Quartile0
0.01
0.02
0.03
0.04
0.05
0.06
∆=0.008 ∆=0.004 ∆=0.009∆=0.008
Actual RHH 2B/PA rates, by projected rate quartilesEx-Fenway 2B/PA rate Fenway 2B/PA delta
SABERSEMINAR 2015 @BLABABOUTBALL
What about for LHH?
1st Quartile 2nd Quartile 3rd Quartile 4th Quartile
-0.00999999999999999
1.04083408558608E-17
0.01
0.02
0.03
0.04
0.05
0.06
∆=0.007 ∆=0.008∆=0.009
∆=0.015
1.19x 1.20x 1.21x
1.34x
Actual LHH 2B/PA rates, by projected rate quartilesEx-Fenway 2B/PA rate Fenway 2B/PA delta
SABERSEMINAR 2015 @BLABABOUTBALL
Do Fenway’s changes matter? Yes…
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1961
1962
1963
1964
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90
100
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Average 2B/PA Fenway Park Effect, by Batter HandL (5 yr avg) R (5 yr avg)
CF flagpole
CF board
Roof suites
EMC Club
Monster Seats
Aux. press boxes
Budweiser RF Roof
Coca Cola Party Deck
SABERSEMINAR 2015 @BLABABOUTBALL
… But not for RHH/LHH weirdness
1960
1961
1962
1963
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2014
2015
-0.010
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
Q4 Delta - Q1 Delta, by Batter HandL (10 yr avg) R (10 yr avg)
CF flagpole
CF board
Roof suites
EMC Club
Monster Seats
Aux. press boxes
Budweiser RF Roof
Coca Cola Party Deck
SABERSEMINAR 2015 @BLABABOUTBALL
So what is the explanation?It’s all about asymmetry:
Data source: Gameday 2007 hit data, converted to feet using method from Peter Jensen: http://www.hardballtimes.com/using-gameday-to-build-a-fielding-metric-part-1/
75th percentiledistance, by
batter quartile
25th percentiledistance, by
batter quartile
SABERSEMINAR 2015 @BLABABOUTBALL
Conclusions Shocking revelation! Some lefties can exploit Fenway’s dimensions more than others.
More interesting: at the extremes, park effects can impact different types of players differently
But… there may not be another park effect like this one, now or ever
SABERSEMINAR 2015 @BLABABOUTBALL
Appendix: Pitchers are not the difference
Avg 2B/PA allowed vs. batter hand Avg wOBA allowed vs. batter hand
Batter group P faced ex-Fenway P faced at Fenway P faced ex-Fenway P faced at Fenway
LHH 4th quartile 0.042 0.046 0.334 0.331
LHH 1st quartile 0.041 0.046 0.335 0.332
Difference 0.001 0.001 -0.001 -0.001
Batter group P faced ex-Fenway P faced at Fenway P faced ex-Fenway P faced at Fenway
RHH 4th quartile 0.041 0.043 0.323 0.329
RHH 1st quartile 0.041 0.043 0.324 0.330
Difference -0.001 0.001 -0.001 -0.001