The split-fingered fastball has become the trendiest pitch in baseball, yet left-handed pitchers continue to shy away from it. Why is that?
During the final years of his Hall of Fame-bound career, Clayton Kershaw experimented with the pitch. After years of struggling to develop a reliable changeup—his delivery didn’t allow enough pronation—he turned to the splitter. In his last three seasons with the Los Angeles Dodgers, Kershaw threw only 126 splitters, but even that minimal usage placed him in an exclusive group of left-handers who throw the pitch.
The splitter has seen waves of popularity before, notably in 1986. But in the modern era of pitch tracking, its usage has never been higher. MLB pitchers are now throwing nearly three times as many splitters as when the league first began tracking pitch types. Eight pitchers have added a splitter they didn’t regularly throw last year, and 11 pitchers did so the season prior.
Despite this surge, the usage is lopsided. Right-handed pitchers are four times more likely to throw a splitter than left-handers. From 2022 to 2025, righties threw more than 11 times as many splitters as lefties. So why are southpaws reluctant to embrace the pitch? There’s no definitive answer, but several theories persist. We tested the four most common ones.
**The Injury Risk Theory**
One recurring concern is the splitter’s impact on a pitcher’s arm. Does the grip cause harm? “The reason I don’t throw the splitter anymore is because I blew out my elbow while throwing it,” said San Francisco Giants lefty Robbie Ray. “I don’t think there’s a direct correlation, but it happened. I was throwing it a lot in spring training, working on it, and never had issues. I think my elbow was just ready to go.”
The belief that splitters lead to elbow injuries has long circulated, but hard evidence is scarce. Research by Jeff Zimmerman of FanGraphs found that pitchers who throw the splitter at least 10% of the time land on the injured list 54% of the time in any given year. Those who don’t throw it? That figure is only slightly lower at 52%. This mirrors previous studies showing no direct link between the pitch and injury risk.
Still, the possibility can’t be dismissed outright. When you grip the ball between your first two fingers, the forearm and elbow muscles engage differently than with a traditional fastball. Those muscles may redirect stress away from the elbow ligament. “I always thought that if thrown properly—with fingers really split like a forkball—that’s when you can get hurt because there’s no resistance against the ball being thrown, and it puts a lot of pressure on the elbow,” former Rays manager Joe Maddon told the Associated Press in 2011.
At this point, the injury risk remains a hypothesis. Advances in player science might eventually measure the splitter’s true effect on the elbow, but current biometrics only break pitchers into skeletal models—they can’t yet track individual muscle activity.