How much is Jenrry Mejia’s sports hernia affecting his pitching?

In early August, Mets closer Jenrry Mejia said he had been pitching through pain – due to a sports hernia – for three weeks (ESPN, Aug. 10). There is less than two weeks left to the 2014 season and – considering how the Mets handled David Wright‘s nagging shoulder injury – should they also consider shutting their young closer down for the remainder of the season?

Ben Berkon, MetsBlog Contributor: “Dear Mr Mejia, I pitched with sports hernia in 2010, results will not get better because you won’t be able to finish your pitches,” former Mets reliever Tim Byrdak recently said on Twitter (Byrdak, Aug. 10).

Nevertheless, despite the injury, and despite beginning the year as a starting pitcher, the 24-year-old Mejia has had consistent success out of the bullpen. To date, he has a 2.98 ERA, a park-adjusted 3.36 xFIP, and 2.95 strikeouts-to-walks ratio with 26 saves since May 12. And, aside from a mild 1.61-point increase in his ERA since July 22, which is when I assume he started feeling pain, Mejia’s peripherals have been relatively stable.

In fact, his zone (pitches thrown within the strike zone), whiff, and line drive rates have all been on par with the pre-injured version of himself.

Time Zone% Whiff% LD%
Pre-Injury (5/12-7/18) 39.1 13.4 25.0
Post-Injury (7/22-9/15) 39.4 13.9 26.0

However, Mejia’s already solid 45 percent ground-ball rate has spiked to an elite 57.9 percent level. Given the 12.9 percent bump in grounders, is it possible Mejia is actually pitching better with the sports hernia?

It’s difficult to pinpoint for sure, but according to Bleacher Report’s injury expert Will Carroll, pitchers do tend to compensate for pain.

​“There will be some adjustment,” Carroll said in an email interview. “Any adjustment could create problems both of force and control.”

In Mejia’s case, the reliever seems to have made positive adjustments.

According to FanGraphs, his change up has accounted for 67.9 percent of his induced ground balls in 2014. And whether it’s a coincidence or not, his change up’s release point has noticeably differed since July 22. His change up’s movement has also changed. Arm slot affects movement, as Matt Lentzer once pointed out at The Hardball Times – so in Mejia’s case, while unique given his injury, it isn’t surprising on the surface. According to Brooks Baseball’s movement charts, Mejia’s change up has been dipping (vertical) at about 1.67-inches more on average since May. Mejia’s change up has also steadily moved more toward the right of the strike zone, from the catcher’s perspective (horizontal).

Even though Mejia’s improved change up and ground-ball rate are noteworthy, more importantly, the Mets have to weigh whether continuing to let him pitch through pain is necessary. Unlike an elbow or shoulder injury, Carroll pointed out that sports hernias have a comparatively light surgical and recovery process.

​“Like many injuries, they can be managed,” Carroll said. “If he’s pain free and not changing his mechanics significantly [or for the worse], there’s usually no need to rush. The surgery is relatively simple, but has a six-week recovery period. Most pitchers (and players) that have had it come back well and with no complications.​”

Assuming Mejia’s pain is actually manageable – and his team’s medical staff has been closely monitoring his health – they could continue to use the reliever when needed. But, if you’re of the belief that players – specifically young pitchers – should not play through pain, then perhaps the Mets should be more proactive in a dwindling, insignificant season.