Speaking to reporters on Tuesday, Glasnow said he believes the injury was caused by changes in his pitching mechanics due to MLB's impending crackdown on pitchers using sticky substances to improve their grip.
"I just threw 80 something innings and you just told me I can't use anything. I have to change everything," Glasnow said, according to Rays TV reporter Tricia Whitaker. "I truly believe 100% that's why I got hurt. I'm frustrated MLB doesn't understand. You can't just tell us to use nothing. It's crazy."
Major League Baseball announced earlier in the day it would begin suspending pitchers who are caught using any kind of foreign substance on the ball, their hands or their uniform – except for the rosin in a pitcher's rosin bag. Enforcement is set to begin June 21.
Glasnow is among several MLB players who have been critical of the new rules, especially with the changes being enacted in the middle of the season.
“Sunscreen and rosin is apparently the same as Spider Tack. Alright I guess I’ll adapt and learn," he added. "And the only thing I learned was that it hurts to throw a ball in the middle of the season, from having something to not having something.”
Glasnow admitted using a mixture of sunscreen and rosin to help him grip the ball earlier this season, but said he didn't use anything in his last two starts. He struck out 11 batters in a victory over the Washington Nationals on June 8, but felt sore afterward.
Then, in his start Monday night against the Chicago White Sox, he exited after only four innings after experiencing what he called "a little tug" in his pitching elbow.
Injuries to the ulnar collateral ligament are often precursors to Tommy John surgery, but the Rays say Glasnow will try to treat the issue with rest and rehab in hopes of returning later this season.
In 14 starts this season for the first-place Rays, Glasnow has a 5-2 record with a 2.66 ERA and 0.93 WHIP. He also ranks second in the majors with 123 strikeouts, just behind Cleveland's Shane Bieber.
He also becomes the third high-profile starting pitcher to go on the injured list in two days – joining Bieber, out with a shoulder strain, and the Washington Nationals' Max Scherzer, who is sidelined with a groin injury.
This article originally appeared on USA TODAY: Tyler Glasnow injury: Rays ace has partially torn UCL in elbow