Advantages for Lefty Catchers
There are not many advantages for left-handed catchers, but there are a couple:
- Fielding bunts/nubbers in front of home plate. The left-hander has an easier throw to first base after fielding a ball in front of home plate. This is especially true for a ball fielded up the third base line, where a right-handed catcher would have to rotate his body about 180 degrees to be able to make a strong throw to first base.
- Catching breaking pitches from right-handed pitchers. With the glove on the right hand, a lefty catcher would be in better position to catch low outside (to a right-handed batter) pitches. A righty will often have to backhand that pitch, while a lefty can frame it normally (perhaps coaxing a few extra called strikes from the umpire). Of course, the opposite is true for a lefty-pitcher, left-batter combination, but there are fewer of those.
What Bill James Said
Bill James himself comments on the left-handed catcher issue in his Historical Baseball Abstract. James writes:
The notion that a left-handed person could not be a major league catcher is absurd...The biggest reason there are no left-handed catchers is natural selection. Catchers need good throwing arms. If you have a kid on your baseball team who is left-handed and has a strong arm, what are you going to do with him?The answer to the question is, of course, turn him into a pitcher.
This actually sounds like a pretty good reason to me. Pretty good, but not perfect. I agree that there'd be a tendency to move lefties who can throw into pitching roles, but I find it hard to believe that every single strong-armed lefty would end up on the mound. Maybe the kid doesn't like to pitch. Maybe he likes to wear shin guards. Maybe his hero is Brad Ausmus. If natural selection were the primary force at work, I think you'd see a preponderance of righties behind the plate, but an occasional lefty would come along. But they haven't, at least not in the last 100 years or so.