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September 2, 2004

The Disappearing Southpaw

Tracing a Decline in Left-Handed Pitching

by James Click

When I was growing up, my father, in an effort to increase my chances of making the major leagues, would make me do things left-handed. It started with small things like using the television remote, washing the dishes or clipping my fingernails (that one was tricky), but eventually it got to the point where he would burn my right hand to keep me from using it.

OK, so none of that is true (relax, Mom). But it has been true throughout baseball history that left-handed people have a spectacularly better chance than the rest of us of reaching the major leagues. Worldwide, the percentage of people who are left-handed is somewhere on the order of 4%, but in baseball the percentage is much, much higher. Left-handed batters (who aren’t necessarily left-handed people) enjoy a positive bias because they are more rare and because they typically have a positive platoon split against right-handed pitchers, a group that forms the majority of hurlers. Likewise, southpaws are prized because they can reverse that advantage.

In the last 10 years, though, the percentage of batters faced by left-handed pitchers has dropped off dramatically:

This graph might be a little misleading, since it’s blown up to the 20-40% range, but considering the stability until about 1992, the change is dramatic. Despite the roughly 4% increase in the last two seasons, southpaws are facing fewer batters now than they have for more than 20 years.

There are several possible explanations for this. The first was that there was a preponderance of star left-handed pitchers in the 1970s and '80s who have been replaced by star righties in the 1990s and 2000s. Of course, there were plenty of star right-handers during the 1970s and 1980s and there are plenty of top flight left-handers (Randy Johnson, anyone?) who have been dominating the game for the past decade. Furthermore, since the decline is in batters faced and not necessarily performance against those batters, it makes sense that perhaps the fault would lie more with the inning-eating middle class of left-handed pitchers.