Platoon
From BR Bullpen
A Platoon is when two players share a position. The most common platoon uses a left handed batter against right handed pitching and a right handed batter against left handed pitching. Other kinds of platoons, like a good fielder/weak hitter and a weak fielder/good hitter are possible, but it's safe to assume a left/right platoon unless otherwise specified.
The key to a traditional left/right platoon is that most batters hit better against opposite handed pitching than against same handed pitching. There are several reasons why this is the case. One major reason is that batters have an easier time seeing the ball when it's thrown by an opposite handed pitcher. Another important reason is that breaking balls tend to break away from same handed batters and in toward opposite handed batters, and most batters have an easier time adjusting to inward than outward break.
The difference between a batter's performance against opposite handed pitching and same handed pitching is his platoon split; a right handed batter who has a .300 batting average against lefies and .250 against righties has a .050 platoon split for batting average. A batter whose platoon split is negative has a reverse platoon split. A batter with a normal platoon split who is hitting against an opposite handed pitcher has the platoon advantage.
Baseball players have understood the advantages of platooning from the very early days of the game. Switch hitting, a strategy that only makes sense in light of the platoon advantage, was in use from the beginning of the National Association. Although players understood that they had an advantage against opposite handed pitching, early teams' rosters were too small to take advantage by having formal platoons.
The first really noteworthy example of platooning was the 1914 "Miracle" Braves. The Braves took advantage of enlarged rosters to platoon at several positions, and unexpectedly won the pennant and the World Series. Braves' manager George Stallings was hailed as a genius, and platooning swept through baseball. Despite its advantages, platooning became less popular in the 1930's and 1940's until it was reintroduced by Casey Stengel of the Yankees. While platooning's popularity has waned and waxed since Stengel's day, it has never gone away completely.
