Zack Wheeler’s smooth reintegration into the Philadelphia Phillies’ rotation stands as one of the franchise’s biggest early season priorities. His recovery from thoracic outlet syndrome has mostly progressed well, an encouraging sign for a team eyeing a World Series push.
Expected to rejoin the club in April, Wheeler’s activation will provide Philadelphia with new strategic options including the possibility of temporarily shifting to a six-man rotation. Such a move could help protect Wheeler’s health while easing the burden on a starting staff that will be essential to a deep postseason run.
However, as Wheeler continues rehabbing at Lehigh Valley, there are still reasons for caution. His velocity has not yet returned to its previous level, and the gap between where he once was and what he’s showing now is significant enough to raise concern. A pitcher who has typically averaged around 96 mph on his fastball, Wheeler recently sat at just 92.7 mph and topped out at 93.9. While velocity alone doesn’t determine success, this isn’t a slight decline and it may carry important implications.
Understanding Wheeler’s diagnosis and whether Phillies fans should worry
To judge how concerned fans should be, it’s necessary to look more closely at Wheeler’s specific condition. Though his operation has generally been described as surgery for thoracic outlet syndrome, there are three forms of the disorder.
Wheeler had the venous type, meaning a vein running through the shoulder and into the neck was being compressed. Surgeons removed a rib to relieve that pressure and address clotting in the area. This differs from the neurogenic version, caused by nerve compression and more common among MLB pitchers and the same condition that derailed Stephen Strasburg’s career.
Thoracic outlet syndrome itself is uncommon. A study in the Orthopedic Journal of Sports Medicine found that from 2001–2019, only 26 pitchers had the rib-resection surgery Wheeler underwent; 81% returned successfully, with no significant performance drop noted. Another study covering 2001–2017 identified 27 pitchers treated for TOS only seven of whom had the venous type and 74% of them made successful returns without major decline.
These results are encouraging, but also come with caveats. The total sample size is small and even smaller for pitchers with Wheeler’s exact condition. Additionally, in one study the median pitcher age was just 28.6. Wheeler turns 36 on May 30, and his arm has already logged heavy mileage.
All things considered, it’s too early for alarm, but this remains a serious, somewhat uncertain situation. Wheeler’s velocity could very well rebound as he continues rehabbing — which would quiet the concerns. But it’s also possible that this reduced velocity is his new norm, forcing him to adjust his approach. For now, the Phillies should monitor him closely and begin planning ways to manage his workload so he’s best positioned to contribute once he’s back on the mound.
