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Monday, May 01, 2006

Platooning in 1922

As I mentioned in a previous post Retrosheet now has data from the 1922 National League. I downloaded it this evening along with the 1993-1998 data to push my play by play database to over 5.8 million rows.

One of the things I wanted to look at given my recent columns was whether the platoon splits differed during that time. Here are the results.

Throws Left Throws Right Platoon Split
L 1602 0.263 0.309 0.324 9632 0.306 0.356 0.436 0.043 0.047 0.112
R 5518 0.303 0.341 0.428 15021 0.281 0.318 0.380 0.022 0.023 0.049

I took out switch hitters. By comparison the 1970-1992 data I used in a previous column showed split differences that weren't quite as large. For example for left-handed hitters it was 24, 26, and 56 points in AVG, OBP and SLUG and for right-handers it was 17, 19, and 33. For the 1922 National League therefore the splits were almost 100% higher for left-handed hitters and about 50% higher for right-handed hitters. Could it be the case that split differences have actually shrunk over time or is this simply a case of small sample size?

I took a quick look at my 1970-1992 data set by year and didn't see any noticeable trend in either direction. There is a lot of variability in the data, especially for lefties where the difference in slugging percentage can go from 44 points one season to 75 the next as it did from 1985 to 1986.

Of course the data since 1970 may not show the trend and so I'll probably need to load all of the data back to 1957 and then take another look.

Steve Goldman of Baseball Prospectus alerted me to the fact that the 1922 data bore out the oft-told story that Casey Stengel learned about platooning from his manager John McGraw who sat the lefty hitting Stengel against southpaws. I ran a query to confirm this and it shows that Stengel batted 246 times against right-handers and just six times against lefties.

However, I'm wondering if the 1922 is missing some games or at bats since the data I loaded contains 252 plate appearances for Stengel that season and baseball reference has him for 283. Hmmmmm.

Casey Stengel 1922
R 246 216 82 7 9 6 15 19 1 7 1 2 0.380 0.439 0.579
L 6 6 3 0 0 0 0 0 0 0 0 0 0.500 0.500 0.500

1 comment:

Dan Agonistes said...

FYI...SABR's Thed Turocy was kind enough to point out that the older Retrosheet files aren't 100% complete play-by-play but that instead some games are only presented in the new "boxscore" file format, which is an additional file zipped with the event files.

He noted that New York coverage is traditionally pretty good in that time period, so that's why I was able to get a significant fraction of Casey's PAs that year. However, there are still some gaps where play-by-play has not yet recovered
(often, because the best source papers didn't publish on Sunday).