Little more than a month of the 2020 season had passed when Merrill Kelly walked into manager Torey Lovullo’s office to deliver the news.

Emotions were heavy. Then Kelly made Lovullo a promise.

“I will do everything that I can to get back and be even better and stronger by the start of next year,” Kelly said.

The Diamondbacks righty was planning to undergo thoracic outlet surgery — a procedure that, while more effective than ever, has a history of ending pitching careers early.

Even with multiple days in the hospital and a four-to-six month recovery timeline awaiting him after the surgery, Kelly had already been through a lot. On Aug. 24 — roughly two weeks earlier — he was scratched from his start against the Colorado Rockies in what was originally announced as right shoulder nerve impingement. 

It came at a difficult time. The Diamondbacks were in the midst of a five-game losing streak and Kelly was one of the team’s few bright spots. In five starts, he was 3-2 with a 2.59 ERA, 29 strikeouts and just five walks over 31.1 innings.

Despite those results, he had been experiencing a plethora of bizarre symptoms, including discoloration, coldness and uncharacteristic fatigue in his throwing arm. Treatment wasn’t helping and he couldn’t pitch through it any longer.

Matt Herges, the Diamondbacks’ pitching coach at the time, found out shortly before the game and rushed into the training room.

“He was just sitting on the table, just totally dejected,” Herges said. “He looked up at me and just kind of shook his head. I just said, ‘I’m sorry. I’m sorry, brother. I get it. I’m sorry.’”

No major-leaguer likes to miss games, but the situation only got worse when Kelly learned he had a blood clot in a vein in his throwing shoulder. Left untreated, it could put his life in danger.

“When I heard blood clot, baseball stopped,” Kelly said. “We need to get rid of this first and foremost because that’s obviously going from not pitching again to maybe not being alive.”

The coaching staff shared Kelly’s concerns.

“That night, we all collectively held our breath and thought, ‘Wow, we dodged the bullet here,’” Lovullo said. “Thank goodness he spoke up.”

Kelly underwent surgery that successfully removed the clot. Unfortunately, as part of the process, a venogram uncovered a narrowed and scarred area in the vein that contained the clot. Texas Vascular Associates surgeon Dr. Gregory Pearl said that’s a clear indicator of thoracic outlet syndrome (TOS). 

Shortly thereafter, Pearl performed Kelly’s TOS surgery in Dallas. The procedure involved removing Kelly’s first rib and a muscle out of his neck to relieve the compression of the blood vessels in his throwing arm.

There are three types of TOS: neurogenic, venous and arterial. Kelly’s symptoms were primarily consistent with venous TOS, which carries a relatively favorable outlook, particularly if diagnosed early.

That’s not to say returning from TOS is easy. There are plenty of success stories, but there are also stories of men such as Matt Harvey, who was one of the game’s best pitchers with the Mets before undergoing TOS surgery in 2016. Since then, he’s 21-38 with a 6.15 ERA, 1.52 WHIP and 6.9 K/9 in 446.2 innings with five different teams.

Tyson Ross had the surgery in 2016 after back-to-back 30-plus start seasons in 2014 and 2015 in which he posted a combined 3.03 ERA for the Padres. He was never the same, posting a 5.19 ERA in 234 innings from 2017 through 2019 with four different teams.

Former Cardinals pitcher Chris Carpenter had the surgery in 2012 and threw only 17 big-league innings the rest of his career. The list goes on.

The ulnar collateral ligament tear is the most infamous injury in baseball. It takes a year or more to recover, and books have been written about its victims.

You won’t find books about victims of TOS. That’s not because TOS hasn’t had a detrimental impact on pitchers. It’s because it’s far less common and far less understood. Pearl, who has performed hundreds of TOS surgeries, said the procedure is more treacherous than Tommy John surgery.

“It’s a bigger operation with a little tougher recovery on the early side of things because we’re taking take out a rib, and we’re working around major blood vessels and the major nerves supplying the arm,” Pearl said. “Tommy John recovery is probably more predictable.”

Pearl said that TOS surgery has improved over time, and Kelly is an example of what it can do. Sure, he’s down a rib and a neck muscle, but he probably wouldn’t know it if his doctor hadn’t told him — and if he hadn’t seen the rib floating in a cup on his way out of the hospital.

“They offered it to me,” Kelly said. “On the way out of the hospital room, it was sitting right there on the counter.”

In the past, TOS surgery patients such as Carter Capps have made their rib into a necklace.

“I said, ‘No, I’d rather leave that part of my life behind me,’” Kelly said, laughing.

All indications are that Kelly has done exactly that. His recovery was smooth. He says he has no lingering effects. And he’s pitching better than he ever has.

“There’s a theory that pitches are like snowflakes,” Herges said. “There’s no two throws that are the same.

“Merrill Kelly [is] one of the guys that comes close.”

Kelly’s ability to repeat his delivery and command the baseball is one of the main reasons he’s sitting at a 1.27 ERA with 26 strikeouts and just seven walks through his first five starts of the season. He currently ranks eighth among all MLB pitchers with 0.9 fWAR.

From a pitch arsenal standpoint, Kelly is using his changeup a career-high 22.1 percent of the time, and for good reason. The offering has averaged two additional inches of both horizontal and vertical break this year, leading to a higher whiff rate and an extremely high 69.6 percent ground-ball rate on the pitch. Opposing hitters are batting .182 with a .212 slugging percentage when they put it in play.

Kelly acknowledges that his changeup has made strides, but he chalks up his success to his mindset more than anything else.

“I know I can get big league hitters out now,” Kelly said. “It’s my fourth year on the team. I know the staff, I know the coaches, I know how we operate. I know where I fit.”

Kelly is still only a few years removed from pitching in Korea, where he reinvented himself over three years after getting stuck in the Rays’ minor-league system.

In some ways, 2022 is the first normal season he’s had in the majors. In 2019, he had just reacclimated to living in the U.S. and the pandemic wiped out more than half the 2020 season. Last year was his first season back after major surgery.

Diamondbacks catcher Carson Kelly spent some time catching Kelly over the offseason and he recognized that something was different.

“There was a little bit of fire in him,” Carson said. “There was more intent with every single bullpen.”

Kelly is arguably the best free-agent signing of general manager Mike Hazen’s tenure. He also overcame a surgery that many pitchers could not.

He made good on his promise.

“Congratulations,” Lovullo told Merrill after his first start back, in a moment he said that he will never forget. “You made a promise to me that you kept.”

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Top photo: Jeff Curry/USA TODAY Sports