Do splitters ruin arms?

Hold a baseball with a splitter grip. Right away, you'll notice the extra tension it puts on your elbow and forearm when compared to a fastball grip. Bruce Sutter introduced the pitch in the late 70s and 80s, and Roger Clemens built a career around an explosive fastball and a devastating splitter. For a while the splitter was in vogue. Nowadays, the splitter has fallen out of favor. Splitters account for only a little more than one percent of all pitches, and several organizations have gone so far as to forbid young players from learning the splitter. Concerns over its effect on pitchers' arms have overhadowed its effectiveness.

Lets take a look at the injury history of pitchers who utilize the splitter. From 2010-13, there have been about 15 starting pitchers per season who use their splitter with at least a ten percent frequency.

2010 was a good year health-wise for splitter-throwing pitchers. Penny accounted for nearly half the time missed, and his injury was an oblique strain. As a group, these 16 pitchers missed a total of 300 days, with only a quarter of them missing any time at all (though Morrow was subjected to an innings limit).

In 2011, six of the fifteen pitchers ended up on the DL, with two of them undergoing season-ending surgery. In all, there were 401 days missed. Notice that Penny cut his splitter usage in half upon returning from injury and Morrow scrapped the pitch for the 2011 season.

Half of these sixteen pitchers landed on the DL, missing a whopping total of 736 days. It bears mentioning that the time missed by de la Rosa and most of the time missed by Matsuzaka resulted from an injury suffered the prior year.

Six out of fifteen pitchers did time on the DL, missing a total of 400 days. Overall, 24 out of 62 pitchers landed on the DL, That number might look high, but it matches up exactly with Jeff Zimmerman's finding that the average starting pitcher has a 39 percent chance of going on the DL. The average DL stint for splitter throwers is 77 days and the median is 74 days. That's higher than the average of 69 and the median of 51 for all pitchers, so perhaps splitter throwers are more likely to have major surgery. In general though, the results for these pitchers are pretty close to that of the general population of major league starting pitchers.

Obviously, this isn't the full picture. There's some selection bias in that I've picked pitchers whose arms have been able to handle the splitter to some extent. For every pitcher listed here, there could be several others who gave up on the splitter early because it bothered their arm. Furthermore, I don't have a handle on how many minor league pitchers have suffered arm injuries due to splitter usage, or pitchers who have been relegated to the bullpen due to their splitter usage. Finally, there could be a myriad of other factors causing the injuries besides the splitter.

Still, it doesn't appear that pitchers who are throwing a splitter are at a higher risk of injury than pitchers who do not. Given that the 18 starters who have thrown at least ten percent splitters since 2002 have been five percent better than their counterparts, perhaps some teams are being a little too quick to decry the splitter.

. . .

Statistics courtesy of FanGraphs, Brooks Baseball and Baseball Heat Maps

Chris Moran is a former college baseball player and current law student at Washington University in St. Louis. He's also an assistant baseball coach at Wash U. In addition to Beyond The Box Score, he contributes at Prospect Insider and Gammons Daily. He went to his first baseball game at age two. Follow him on Twitter @hangingslurves