Tigers pitcher Casey Mize, the first overall pick in 2018, will undergo Tommy John surgery

Detroit Tigers right-hander Casey Mize will undergo Tommy John surgery, manager A.J. Hinch said Friday afternoon, to repair the ulnar collateral ligament in his throwing elbow.

He will miss the rest of the 2022 season. 

Dr. Keith Meister, the team physician for the Texas Rangers, determined Mize needed elbow surgery. The procedure will occur "pretty soon," Hinch said, but the exact date is unclear. The recovery process usually takes 12-18 months, meaning Mize is unlikely to return to the Tigers until 2024.

"He still doesn't have a torn ligament," Hinch said. "Dr. Meister has diagnosed him with a stretched ligament that's lost its elasticity and functionality inside his elbow. Any of the exams we've had, it's shown an intact ligament, which is true. But the symptoms continue to recur."

Mize, the 2018 No. 1 overall pick, hasn't pitched for the Tigers since April 14 against the Kansas City Royals at Kauffman Stadium. The 25-year-old landed on the injured list April 15 with a right elbow sprain.

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At first, the Tigers believed Mize avoided a significant injury.

"When they told us the ligament was intact, that gave us great confidence that there wasn't going to be a big problem," Hinch said. "The fact that it is intact but yet he still needs surgery is part of the medical side that I have no idea about. But it's the reality."

Mize initiated two throwing programs in hopes of a non-surgical recovery.

Both times, though, he was shut down because of soreness.

The Tigers halted his throwing program for the first time after a May 12 start with Triple-A Toledo, in which Mize allowed three runs and couldn't complete the first inning. His throwing program was stopped again this week due to a setback when he attempted to play catch from 90 feet on flat ground.

"I don't think any of this is an exact science," Hinch said. "You don't want to race to the surgery table, despite how successful it's been. The time lost is sometimes needed for recovery but sometimes needed for diagnosis."

Mize has pitched 39 games for the Tigers in parts of three seasons, making his MLB debut in August 2020. He led the team with 30 starts and 150⅓ innings pitched last season, to go with a 3.71 ERA.

This season, Mize posted a 5.40 ERA with two walks and four strikeouts across 10 innings in two starts.

Hinch spoke to Mize on the phone Thursday night.

"Resolution for this is the No. 1 key," Hinch said. "He knows the problem. He knows the answer. He knows what the road ahead is. ... I know he's going to be a diligent patient. I know he's going to do everything that's asked of him to rehab this and get back to being the pitcher that we know he's going to be moving forward."

Most recently, Tigers right-hander Spencer Turnbull underwent Tommy John surgery in July 2021. He is on track to return in September 2022. Also, righty Alex Faedo — one of Mize's close friends — had the surgery in December 2020 and returned to games in March 2022.

Faedo was called up for his MLB debut last month, which led to a successful start to his big-league career. He boasts a 2.92 ERA, 11 walks and 28 strikeouts in 37 innings across seven starts.

"I've had a number of pitchers in my managerial career that have had it, whether it's Justin Verlander or Lance McCullers Jr.," Hinch said. "Unfortunately, you can rattle off a lot of names. Certainly Michael Fulmer, being another one that can give some advice during the pre- and post-surgery days."

Fulmer had the elbow surgery in spring 2019, following a knee injury that ended his 2018 season. He returned to the mound with the Tigers in July 2020, though the team kept him to a strict innings limit, with all 10 of his starts that season at three innings or less. 

He was green-lighted for longer stints in 2021, though he was soon moved to the bullpen, where he has found success. After averaging 95.8 mph on his fastball during the 2017-18 seasons, his velocity dropped to 93.1 mph during the 60-game 2020 season. Last season, in which he made 52 appearances (69⅔ innings), his average fastball was back at 95.3 mph.

The added velocity made a big difference in Fulmer's confidence, and his success out of the bullpen last season.

"Last year, trying to pitch at 92-93 (mph) because that's all I had at the time didn't work out well, because I really never had to do that before," Fulmer said in May 2021. "Do I think if the velocity was still down the way it was last year, I would have figured it out? Absolutely. But it's a lot easier when I can trust myself, trust my body and let loose on everything."

Verlander is a more recent Tommy John success story, though his rehab took longer. He was injured in July 2020, while throwing six innings in the Houston Astros' season opener. He missed the remainder of that season, and sat out all of 2021. This season, however, the 39-year-old appears back to form, with a 2.11 ERA, 73 strikeouts and 14 walks over 71⅔ innings (in 11 starts). His fastball, which averaged 94.9 mph in 2020, is at 94.8 mph this season.

Contact Evan Petzold at epetzold@freepress.com or follow him on Twitter @EvanPetzold.