Left-handed pitching has long been one of the most prized commodities in professional baseball. Teams strive to obtain lefty pitchers, and southpaws recognize their competitive edge. Two-sport athlete Tom Glavine explained his career choice this way: “I love both sports, but the deciding factor was, being a left-handed pitcher, I had a huge advantage in baseball because of that, and I didn’t have that type of advantage in hockey.”
Even a century ago, Tris Speaker expressed the sport’s reverence for southpaws — if falling short as a trade analyst — when he reportedly opined that “taking the best left-handed pitcher in baseball and converting him into a right fielder is one of the dumbest things I ever heard.”
MLB rosters reflect this preference for lefties today. Although just 10 percent of American males throw with their left hand, fully 28 percent of innings thrown by MLB pitchers in the past decade2 — and 29 percent of starts — came from the left side. Remarkably, lefty pitchers make it to the big leagues about three times as frequently as righties, given their share of the general population. What accounts for this huge surplus of southpaws?