CHICAGO -- Rays right-hander Tyler Glasnow was placed on the 10-day injured list on Tuesday after being diagnosed with a partially torn UCL and a flexor strain in his throwing arm.

Glasnow had an MRI in Chicago on Tuesday morning, a day after exiting the Rays’ 5-2 win over the White Sox on Monday night due to right elbow inflammation. Tampa Bay said that a timeline for Glasnow’s return will be determined after further medical evaluation, and he is scheduled to visit Dr. Keith Meister on Friday.

Glasnow said the initial medical recommendation was that he can rehab from these injuries without undergoing Tommy John surgery, but Tampa Bay’s ace was clearly emotional on Tuesday. 

He said Monday night that he experienced “a little tug” in his right elbow after throwing a fastball to Andrew Vaughn, the final hitter he faced in the fourth inning. He threw three more pitches to finish the inning, saying he felt “a pull every time I threw” each of them, then reported that tightness to pitching coach Kyle Snyder and head athletic trainer Joe Benge after returning to the dugout. 

Glasnow noted that the ball was “extremely slick” on Monday night, which made it difficult to grip. When he sat down for an interview on Tuesday afternoon, he seemed even more convinced that was a factor in the injury. 

“I know the timing is convenient, but I 100 percent believe that contributed to me getting hurt,” Glasnow said.  

Glasnow also explained that he previously used “sticky stuff” -- sunscreen and rosin, which he said aids his grip but didn’t affect the quality or spin rate of his pitches -- but stopped doing so before his June 8 start against the Nationals at Tropicana Field. That night, Glasnow struck out 11 and walked only one batter over seven innings, but he felt the difference the following day. 

“I woke up the next day and it was like, ‘I am sore in places that I didn't even know I had muscles in.’ Like, I felt completely different,” Glasnow said. “I switched my fastball grip and my curveball grip. I've thrown it the same way for however-many years I played baseball. I had to change.” 

He said he didn’t feel “crazy pain” initially and wondered if he could have thrown another inning considering he managed to finish the fourth, but he didn’t return to the mound. He didn’t appear to be in serious pain at any point, although television cameras caught him shaking his right arm at times near the end of his outing at Guaranteed Rate Field.  He worked a clean fourth inning, striking out Yasmani Grandal and Adam Eaton to begin the frame. At that point, he said, he gripped a new, slick baseball “really hard” and threw a 98.2 mph fastball that Vaughn fouled off. He felt the pull then and on each pitch after that. 

The discussion of “sticky stuff” has been gaining steam in recent weeks, but the league has been focused on addressing it going back to Spring Training. Major League Baseball sent a memo to clubs in March saying it would step up the monitoring and enforcement of rules prohibiting pitchers from applying foreign substances to baseballs. And the new rules announced on Tuesday that are being instituted next week are a result of the league’s findings over the first two months of the year. MLB’s efforts this season have been endorsed universally by the Competition Committee, and the league has notified the Players Association and the Major League Baseball Umpires Association of this increased enforcement of the rules.  

Going back to 2016, the league has been looking into developing a stickier ball, including experimenting with a tackier ball in the ’16 Arizona Fall League and introducing a prototype for a day during Spring Training ’19.  

“Whether you want us to not use sticky stuff or not is fine. Do it in the offseason. Give us a chance to adjust to it,” Glasnow said. “I had to change everything I've been doing the entire season … Me throwing 100 [mph] and being 6-7 is why I got hurt, but that contributed.” 

Glasnow has been one of the best pitchers in the AL this season, harnessing his high-octane stuff to put together a 2.66 ERA with 123 strikeouts in 88 innings over 14 starts. The Rays have let him pitch deep into games -- he worked at least seven innings in each of his previous three starts -- but they have also been mindful of his workload. With several off-days built into the schedule earlier this month, Tampa Bay reshuffled its rotation to give Glasnow -- who missed nearly four months in 2019 due to a right forearm strain -- six days of rest before his June 8 start and five days of rest before Monday’s outing. 

“Tyler's such a big part of what we're doing. Look, all 26 guys are. You don't like to see any of them get hurt,” Rays manager Kevin Cash said. “You understand injuries happen, but when these kinds of injuries -- when there's some uncertainty behind them and, in all fairness, it's gonna be a lengthier time for him to get back and contribute -- and what he was doing, he was putting together a really special season. So you feel for Tyler.”