Lefty-Righty Splits on Pitcher Cards

​Some of you may have noticed that the batting averages included on the pitcher cards don't match the numbers on sites like Baseball-Reference.

For example, Johnny Antonelli's 1955 card (at right) lists his "BA vs. L/R" as ".203/.246". The corresponding averages at Baseball-Reference are ".204" and ".244".

There are 3 reasons for this:

1. I had some bad data for the 1955 season. This has been fixed.​

2. The data is incomplete. Most data sources don't include the number of Sacrifice Hits (SH) and Sacrifice Flies (SF) allowed by each pitcher. Because SH and SF aren't counted as at-bats, they need to be subtracted from the number of Batters Faced (BF) to calculate the Batting Average allowed by each pitcher. I estimate SH and SF allowed by each pitcher, causing the "BA vs. L/R" calculations to differ by a few points from other databases.

​3. Lefty-righty stats are incomplete before 1972.
You can find SF and SH if you drill down to individual season splits, but these splits are often incomplete. For example, the "1955 Splits" page at Baseball-Reference for Ruben Gomez shows 111 hits allowed versus righties and 76 hits allowed versus lefties — this is 20 hits short of the total number of hits (207) allowed by Gomez in 1955. Where lefty-righty split stats are missing, I estimate them using a player's career stats.