From the National Library of Medicine on TOS and pitching performance:
Conclusion: 74% of professional pitchers who undergo surgical intervention for TOS are able to return to play at the MLB level. With regards to performance, the majority of metrics were unchanged from prior to surgery, indicating return at a similar functional level.
Pitching metrics demonstrated that pitcher ERA remained inferior postoperatively compared to baseline preoperative performance (3.66 vs 4.50, p = 0.03). Fastball velocity (p = 0.94) and strike percentage (p = 0.50) were equivalent to pre-injury performance.
Me: "Similar" functional level, but still reduced as far as I read it. The ERA difference seems significantly worse. Reports say Chris Archer is a "smart pitcher" and if he can figure out how to be effective post TOS , then he can help the Twins some.