Philadelphia Phillies ace Zack Wheeler will miss the rest of the season after undergoing thoracic outlet syndrome surgery.

Zack Wheeler’s season is over, with the Phillies confirming that he has venous thoracic outlet syndrome (TOS) and will have decompression surgery within the next few weeks.

The anticipated recovery period is six to eight months.

“He will miss this season, but we expect him to return in six to eight months and be the Zack Wheeler we know,” said baseball operations president Dave Dombrowski. “That’s the information we have. Unless something unexpected happens, he should be able to pitch again as before.”

The type of TOS is a key distinction; Wheeler has an acute venous form of TOS, which is entirely different from neurogenic TOS — and the long-term outlook varies significantly.

Wheeler’s TOS case is similar to that of Rangers right-hander Merrill Kelly, who underwent the same surgery in 2020. Kelly had his operation in September of that year — roughly the same timeframe Wheeler is likely to have his — and was ready by spring training, going on to start 27 games in 2021. However, neurogenic TOS eventually derailed Stephen Strasburg’s career and led to his early retirement.

Of course, every case is unique, and no one can predict exactly how Wheeler’s situation will unfold.

“So the recovery might vary somewhat,” Phillies head athletic trainer Paul Buchheit said. “And for him... this is more of an acute issue — which works in his favor because he didn’t suffer from it for a long time before surgery.”

Wheeler was placed on the injured list on August 16 due to a blood clot in his right upper limb. Two days later, he underwent thrombolytic surgery to remove the clot.

Given the severity of the situation and all the unknowns over the past week, manager Rob Thomson expressed relief that the issue has been diagnosed and can be treated surgically.

“He’s healthy,” Thomson said when asked about his initial reaction to the diagnosis. “Losing him is disappointing, but we have plenty of depth in that area. I like our club. So the six to eight months recovery timeline is encouraging.”

While understandably the focus is on Wheeler and his long-term health, no one is overlooking the short-term impact from a baseball perspective.

Over the past five years, Wheeler has arguably been one of the most dominant pitchers in the majors. Since joining the Phillies in 2020, he leads all pitchers in strikeouts (1094), lowest WHIP (1.02), and innings pitched (979), and ranks third in ERA (2.91).

There’s also postseason success; despite strong regular-season performances, Wheeler has been at his best when the spotlight is brightest.

Wheeler’s career postseason ERA of 2.18 ranks third historically among pitchers with at least 10 postseason starts, behind only Waite Hoyt (1.83) and Madison Bumgarner (2.11).

“Yes, it’s a huge loss. He’s a Cy Young-caliber pitcher in the postseason,” designated hitter Kyle Schwarber said. “We know it won’t be easy, but as we get closer to the playoffs, we don’t need anyone trying to be a superhero.”

“If our players can do their jobs, we’ll accept that. We believe in our players.”

The question is: who will those players be?

Without Wheeler, Cristopher Sánchez becomes the unquestioned top starter. Currently, Ranger Suárez and Jesús Luzardo appear to be the most likely candidates to follow Sánchez, forming a trio of left-handed starters.

Ideally, right-hander Aaron Nola will regain form in the final five weeks. Today marks his second start after missing three months due to a right ankle sprain and a right rib stress fracture.

How important is it for Nola to step up and break up the trio of lefties for the Phillies in this brief playoff push without Wheeler?

“Very important. Without a doubt,” Thomson said. “I do expect Nola to perform well. He’s been doing that for a long time. He’s experienced. He’s been through slumps and come back from them. He’ll be fine.”

Wheeler will be fine too.

But he will turn 36 in May next year. Wheeler has indicated he does not plan to pitch through his current contract, which runs through the 2027 season.

Of course, Wheeler has also expressed his desire to win a Cy Young Award and a World Series championship before retiring. This season, he was striving to achieve both.

For Wheeler, the Cy Young will have to wait at least one more season. For the Phillies, the road to the World Series just got a bit tougher.

Setting baseball aside, there is still a sense of relief now that the problem has been identified and can be addressed.

“This isn’t a lifelong condition,” Schwarber said. “You play baseball for a short time in your life. So, we hope he can be completely healthy by the time his baseball career ends, so he can enjoy the rest of his life with his family and kids.”