The Problem with Pitch Clocks

Baseball games have gotten longer over the years, and today they run a little over three hours, on average. That means die-hard baseball fans are spending around ten more hours per season watching their teams than they were just a few years ago. In the face of pressure from those who think games drag on too long, Major League Baseball is considering enforcing a rule that would speed things up by cutting the length of permitted time between pitches.

A new study modeling muscle fatigue in baseball pitchers cautions that cutting a pitcher’s recovery time would likely result in more injuries.

But a new study modeling muscle fatigue in baseball pitchers cautions that cutting a pitcher’s recovery time — enforced with the use of a clock on the field — would likely result in more injuries.

Published in March in the Journal of Sports Sciences, the study concludes that forcing pitchers to quicken their pace would lead to increased muscle fatigue in the arm and added stress on regions like the ulnar collateral ligament, or UCL, which, when injured, could spell surgery and weeks on the bench.

“Trying to take away directly from a player’s recovery time is something that’s a pretty obvious risk factor for injury,” says Michael Sonne, co-author of the study and a post-doctoral researcher at McMaster University in Canada. “As soon as you put this pitch clock in, you’re influencing the duration of rest pitchers will see.”

To build a computational model of muscle fatigue, Sonne gathered data on 73 American League pitchers – including innings pitched, pitches per inning, time between pitches, and the type of pitch thrown (fastballs and curveballs) – from FanGraphs, an online clearinghouse for baseball statistics, and simulated how fatigue set in on the muscles used to stabilize their elbows during throws. The shorter the time between pitches, his study found, the higher the muscle fatigue and the more strain placed on areas like the UCL.

The average time between pitches in Sonne’s study was 22 seconds, with some pitchers winding up after only 17 seconds. A pitch clock, which is already technically required but seldom enforced, would lower this to 12 seconds. That’s too short of a window to recover, Sonne’s study suggests, especially in situations like long innings and protracted games with added muscle stress. And with pitchers these days throwing harder and faster, injuries are on the rise – all the more reason to avoid additional strain with this kind of a rule change, said Sonne.

“We are all aware that UCL tears are on a steady rise in baseball and if the loads on the UCL increase due to initiating a pitch clock we may see that continue,” said Stephen Thomas, an assistant professor of kinesiology who studies throwing injuries at Temple University’s College of Public Health and was not involved in the research. “This study does bring to light the potential harm that can occur with this potential rule change,” he wrote in an email.

Sonne hopes his conclusions will help dissuade Major League Baseball from enforcing a pitch clock, which is already being tested out in the minor leagues. “The best thing that could happen with this is to get it into the hands of the MLB Player’s Association to give the union a little more ammo,” he said.

But baseball pitchers are up against a powerful league that might put complaints from fans ahead of the science. “In a day and age where sports scientists are identifying muscle fatigue as a primary cause of injury,” Sonne said, “if there’s something as glaringly obvious as the risks associated with cutting recovery time, maybe try to shorten commercial breaks.”