Wheeler’s outlook as he returns from TOS — and what to expect in 2026 originally appeared on NBC Sports Philadelphia
When people look back on the 2025 Phillies, the loss of Zack Wheeler will always stand out.
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On Aug. 15, the club revealed that the 35-year-old had a right upper-extremity blood clot. He was placed on the injured list two days later and underwent a successful thrombolysis removal procedure a day later. On Aug. 23, his season was declared over.
It was a gut punch. Wheeler was in the midst of one of his best years in Philadelphia — 10–5 with a 2.71 ERA, an elite 195/33 strikeout-to-walk ratio and a 0.94 WHIP across 24 starts.
The injury buildup
The first hint of trouble came on Aug. 2, when right shoulder soreness after a start versus Detroit pushed his next outing back two days.
Wheeler beat Texas on Aug. 10, but the radar gun told the story. MLB.com’s Paul Casella noted that every pitch type dipped more than one mile per hour, including a 2.5 mph drop on his sinker and a 2 mph dip on his four-seamer.
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So when the IL move became official, it wasn’t shocking — but it was certainly damaging. The Phillies were 17 games over .500. They were past the trade deadline. Their plan to deploy a true six-man rotation to ease Aaron Nola was in the rearview mirror.
More updates would come too. On Sept. 23, Wheeler underwent vascular thoracic outlet syndrome surgery.
The Phillies adjusted — Cristopher Sánchez led MLB in WAR (8.0) and carried the staff down the stretch — however, Wheeler’s absence was felt throughout the club’s unsuccessful trip to the postseason.
Now, with Spring Training roughly three months away, the Phillies have several rotation questions. Can Sánchez handle ace responsibilities across a full season? Can Jesús Luzardo match the production of Ranger Suárez, who is expected to leave in free agency? Who becomes the fifth starter?
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But one question sits above the rest: what version of Zack Wheeler will the Phillies get?
Recent history of ‘TOS’
TOS has become a buzzword for pitchers — and a scary one. Notable starters Matt Harvey, Josh Beckett and Stephen Strasburg all had the surgery. None returned to pre-injury form, and Strasburg never pitched again.
But not all TOS is the same. Vascular TOS — the type Wheeler had — has produced stronger outcomes than the neuronic version that derailed Strasburg’s career.
The clearest example is Merrill Kelly.
Credit: Jerome Miron – Imagn Images
As detailed in Charlotte Varnes’ reporting for The Athletic, Kelly underwent vascular TOS after the 2020 season and returned without delays, making 27 starts in 2021 and posting a 3.66 ERA across 135 starts over the next five seasons.
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Expectations and timeline
That story matters as the Phillies try to evaluate Wheeler’s outlook.
Since joining Philadelphia in 2020, Wheeler owns a 2.91 ERA. If he returns with an ERA in the 3.30–3.50 range, history says that would already qualify as a successful comeback. There’s optimism internally because the Phillies don’t need Wheeler to single-handedly carry the rotation anymore — Sánchez’s emergence has changed that dynamic.
“It helps, but I would rather have Zack Wheeler back and Cristopher Sánchez,” Dombrowski said in his end-of-season presser. “I’ve dealt with thoracic outlet [syndrome] in the past — there are differences in TOS — and I feel much more optimistic.”
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As for the timeline, there have been no updates since mid-October. Per Dombrowski, “The timeline remains six to eight months to be back pitching in a major-league game — so that takes you to end of May. I don’t think it’ll affect us a great deal because we’re looking for him to come back on that timeline.”
That makes an Opening Day return unlikely. But Wheeler will be deep into his throwing progression throughout Spring Training.
It’s difficult to attach firm expectations to a pitcher turning 36 on May 30, especially coming off major surgery. But if there has been one constant during his tenure in Philadelphia, it’s that Zack Wheeler has earned the benefit of the doubt.
The Phillies don’t need Wheeler to recreate his 2021 or 2024 Cy Young runner-up seasons to get back to October. And with recent reporting indicating they won’t pursue a starter this winter, the plan is clear.
If he returns healthy — and somewhere close to his pre-injury form — they’ll have the stabilizer they were missing in their 2025 postseason run.
