The Phillies' starting pitching has been a significant strength for the team throughout 2025, but all of a sudden, the staff may be shorthanded moving forward.
Following August 16's 2-0 loss to the Nationals, Philadelphia's president of baseball operations, Dave Dombrowski, announced that ace Zack Wheeler is being placed on the IL with an "upper-extremity blood clot."
Wheeler has been among the NL's best pitchers not just this season, but throughout his time in Philadelphia. Over his past six starts, he had allowed a somewhat uncharacteristic 17 earned runs in 33.2 innings.
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Here's what to know about Wheeler's blood clot and how it will impact the Phillies' rotation as the team pursues another NL East title.
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Zack Wheeler injury update
Dombrowski told reporters on August 16th that the Phillies are placing Wheeler on the 15-day IL with a blood clot in his right shoulder, which is his throwing arm. ESPN's Jeff Passan initially reported that the timeline for Wheeler's return is "unclear."
The following Monday, the Phillies then announced that Wheeler had undergone a successful thrombolysis procedure to remove the blood clot, with "further treatment and a subsequent timeline of recovery for Wheeler" still to be determined. When asked if Wheeler could return for the 2025 season, manager Rob Thompson said "We don't know."
“Do you think (Zack Wheeler) could pitch again this season?”
— Crossing Broad (@CrossingBroad) August 18, 2025
Rob Thomson: “We don’t know...” pic.twitter.com/eBXXaePQWA
Wheeler's performance hasn't completely fallen off a cliff lately, but there were growing signs of concern for the pitcher. For a No. 1 arm who had previously made 11 starts this season with one earned run allowed or fewer, Wheeler went on a recent stretch that included 17 earned runs allowed over six starts. That stretch also came after a July 6 outing in which he tossed a complete game against the Reds.
On Aug. 10 against the Rangers, Wheeler allowed two runs in five innings with three walks and some decreased velocity. However, the Phillies didn't show too much concern for his dropping numbers at the time, which were still considered good even with a decrease in overall performance.
"I’m not concerned,” Phillies manager Rob Thomson said of Wheeler on Aug. 10, per The Athletic. “They’re working on some stuff, and he just looks a little bit out of sync. The velocity’s not there, but his secondary stuff was good. He got a lot of whiffs.”
According to The Athletic, Wheeler had mentioned "shoulder stiffness" following his Aug. 2 start against the Tigers, which prompted the team to give him some extra rest between starts. The Phillies also had imaging done at the time, but Wheeler was never taken out of the rotation.
“I’m not concerned,” Wheeler said at the time, per The Athletic. “I’ve pitched at [a lower] velo before. It will come back.”
However, that is not the case. the Phillies announced on August 23rd that Wheeler will miss the rest of the season with thoracic outlet syndrome. Wheeler has been recommended by doctors to undergo surgery, which means he would miss between 6-8 months of action.
Philadelphia Phillies ace Zack Wheeler will miss the rest of the season. He was diagnosed with thoracic outlet syndrome and has been recommended to undergo surgery, which would cause him to miss 6-8 months, according to the team.
— Jeff Passan (@JeffPassan) August 23, 2025
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What is Thoracic Outlet Syndrome?
Thoracic Outlet Syndrome is defined as "when nerves or blood vessels are compressed by the rib, collarbone or neck muscles at the top of the (thoracic) outlet," according to Johns Hopkins medicine. The injury is located in the thoracic outlet, which is right below the collarbone.
This is an injury that has impacted pitchers in major league history, and many of them were never the same post-injury. Matt Harvey, Chris Carpenter, Phil Hughes, Josh Beckett and Stephen Strasburg are all among the players who had the injury in their careers.
Phillies rotation without Zack Wheeler
While Wheeler's injury leaves the Phillies without one of baseball's best pitchers for an unknown period, the team does have the luxury of Aaron Nola returning from the IL. Nola hadn't pitched since May 14 due to a rib injury.
With Nola back, he'll join a rotation that is still set to include Christopher Sanchez, Ranger Suarez, Jesus Luzardo, and Taijuan Walker. Until Wheeler returns, which remains up in the air for now, Philadelphia will be relying on some other arms.
Here's a look at Philadelphia's rotation outside of Wheeler:
- Aaron Nola (1-7, 49.2 IP, 6.16 ERA)
- Christopher Sanchez (11-4, 150.2 IP, 2.45 ERA)
- Ranger Suarez (8-6, 112.1 IP, 3.28 ERA)
- Jesus Luzardo (11-6, 139.0 IP, 4.21 ERA)
- Taijuan Walker (4-6, 91.2 IP, 3.34 ERA)
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Zack Wheeler stats
While he's fallen behind Paul Skenes and his teammate Christopher Sanchez in the NL Cy Young race lately, Wheeler's been both one of the most dominant and durable starters in the league this season.
His 149.2 innings this season rank sixth in MLB, while his 195 strikeouts lead all of baseball. Here's a look at Wheeler's stats this season:
- Games: 24
- Record: 10-5
- Innings Pitched: 149.2
- ERA: 2.71
- WHIP: 0.94
- Strikeouts: 195
- Walks: 33