Tyler Thornburg To Undergo Surgery For Thoracic Outlet Syndrome

The Red Sox announced on Thursday that right-hander Tyler Thornburg will undergo surgery to alleviate thoracic outlet syndrome. Thornburg, who has yet to pitch this year due to ongoing shoulder troubles, will miss the entire season.

The team expects Thornburg to be ready for the 2018 season. Per Dombrowski, via Jen McCaffrey of MassLive.com (on Twitter), the medical expectation is that the reliever could be ready for MLB action in nine months’ time. That would land in mid-March, right in the middle of 2018 Spring Training.

[Related: Boston Red Sox depth chart]

Boston acquired the 28-year-old Thornburg this offseason on the heels of an excellent 2016 campaign, hoping that he could help to serve as a bridge from the rotation to closer Craig Kimbrel. However, for the second consecutive offseason, Boston’s top bullpen addition will be unable to contribute to the club due to injury. (Carson Smith underwent Tommy John surgery in 2016 and has yet to take the hill for the BoSox, either.) The trade looks decidedly lopsided at this point, as Boston sent third baseman Travis Shaw and prospects Mauricio Dubon, Josh Pennington and Yeison Coca to Milwaukee in return.

Of course, thoracic outlet syndrome was entirely unforeseeable, and based on Thornburg’s 2016 success, the Red Sox had every reason to be interested in the breakout righty. Last year, Thornburg tossed 67 innings of 2.15 ERA ball while averaging 12.1 K/9 and 3.4 BB/9 with a 32.4 percent ground-ball rate. The former starter also saw his fastball velocity jump to an average of 94.1 mph, and his 12.1 percent swinging-strike rate was comfortably above average among big league relievers. On top of that, Thornburg entered the 2017 season with just over three years of service time, giving Boston three more years of control over the righty before free agency.

The Sox will have another two years to try to recoup some value from the swap, though there’s no guarantee that Thornburg will simply bounce back to his former self. While some pitchers, such as Chris Young and Jaime Garcia, have come back and enjoyed success following the operation, more recent cases such as Phil Hughes and Matt Harvey have struggled upon returning from the same procedure.

Even without Thornburg contributing, however, Boston’s bullpen has been a strength in 2017. Red Sox relievers have the second-best ERA and FIP of any team in the Majors, and their xFIP ranks fourth among big league clubs. Craig Kimbrel has not only bounced back after a down season (by his standards) in 2016 — he’s turned in the best year of his remarkable career to date. Joe Kelly, meanwhile, is sporting a 1.27 ERA, and Matt Barnes has emerged as a reliable setup arm as well. In fact, the Red Sox have eight relievers that have totaled 10 or more innings in 2017, and all but one (rookie Ben Taylor) has turned in an ERA of 3.77 or better.