Of the approximately 150 pitchers to begin this season in the starting rotation of a big league team -- we say "approximately" because some teams have taken advantage of early off-days to avoid using a fifth starter -- 45 are left-handed. That's just below 30 percent of expected starts going to southpaws, which aligns nicely with the actual percentage of plate appearances that came against all lefty pitching last season (29.8 percent).
That's a sizable amount of plate appearances to account for, and so clubs must construct their rosters with the ensuing platoon splits in mind. But not all lefty starting pitching is created equally, and here we're talking about much more than just the obvious differences between Clayton Kershaw and Jeff Francis. Whether by design or by circumstance, left-handed starting pitching is no way dispersed equally throughout the big leagues -- some teams have to deal with up to four times as many southpaw starters in their divisions than others.
By mapping the lefty starters in each division against offensive tendencies, we can identify contenders who are most hurt and helped by the uneven distribution of southpaws.
Hurt: New York Yankees
On Opening Day in the Bronx, the Yankees faced lefty starter Jon Lester and his Boston Red Sox. As one might expect, Yankee manager Joe Girardi attempted to respond by loading his lineup with as many right-handed bats as he could against the Boston southpaw.