In the book “Moneyball”, there was a section where Billy Beane and Paul DePodesta complained about manager Art Howe’s usage of Jim Mecir, a relief pitcher who had a reverse platoon split. He was a right-handed pitcher who was slightly better against left-handers for the entirety of his career. In 2001, he was dominant against lefties and mostly average against righties. However, in 2002, despite continuing the trend of being better against left-handed batters, he faced more right-handed batters than left-handed batters. Obviously this was over a decade ago, and just one anecdotal example, but when I was writing about Miguel Almonte, a Royals prospect who appears to be a reverse split pitcher, I speculated that reverse split relievers have less value than normal relievers because they are usually not used correctly. Of course, this needs to be tested.
I looked at all relievers’ splits by FIP from 2010-2013 with at least 50 innings against both lefties and righties and looked at pitchers were better when they did not have the platoon advantage (reverse splits), taking out the ones with results that weren’t significant (just a few points difference). Out of the 174 qualified relievers, there are about 38 reverse platoon split pitchers, only 4 of them lefties. I then looked at the percentage of hitters they faced with the platoon advantage (that is, hitters they are weaker against because they are reverse split pitchers).
|Name||Throws||FIP LHB||FIP RHB||Platoon Adv %|
The reverse split relievers faced hitters with the platoon advantage an average of 53 % of the time. For comparison, the average right-handed pitcher (including starters) have the platoon advantage 49.6% of the time, and the qualified right-handed relievers in our sample had the platoon advantage 54.6 % of the time, just barely more than the reverse split pitchers. So it does appear that there isn’t a big difference in how reverse split relievers are used and how ones without reverse splits are used.
Some of the worst used relievers by platoon advantage percentage have been Casilla, Ondrusek, Burnett, and Acosta. Burnett has bounced around the waiver wire, while Acosta is having a lost year in Japan. Casilla strangely got an extension. The best used relievers were Bastardo, Soria, and Sipp. Sipp was traded to the Diamondbacks from the Indians, while Soria was the Royals closer, and Bastardo is a piece of the Phillies bullpen.
So in conclusion, some have been used correctly and have had success, and two of them top 4 are actually Royals, but a lot of teams don’t seem to know how to use them properly. One problem is that a few of them are or have been traditional closers, who come in regardless of the platoon. This leads to them facing a lot of hitters with the same platoon, especially if the opposing manager is aware of and acts upon the reverse platoon splits.