Diamondbacks reliever lands on 60-day IL, will undergo thoracic outlet surgery

Diamondbacks reliever Kyle Nelson will undergo surgery to treat thoracic outlet syndrome, manager Torey Lovullo told reporters, via Alex Weiner of Arizona Sports. There’s no official timetable for Nelson’s return to game action, but the Snakes placed him on the 60-day injured list when they called up Brandon Hughes on Tuesday afternoon.

The track record for players, especially pitchers, returning from thoracic outlet surgery is mixed. Players like Matt Harvey and Chris Archer never regained their pre-surgery form, while the condition essentially ended Stephen Strasburg’s career. On the other hand, Nelson’s teammate, Merrill Kelly, has perhaps had the best post-TOS career of anyone to undergo the procedure to date. Kelly recently suffered a shoulder injury but had been healthy and very effective between his 2020 surgery and this April. Nelson’s bullpen mate Ryan Thompson has also rebounded after undergoing a TOS procedure while he was a member of the Rays in 2021.

However Nelson’s long-term recovery plays out, his loss deals an immediate hit to the Arizona relief group. A waiver claim from the Guardians three years ago, he owns a 3.47 ERA in 114 innings with the Snakes. Nelson outperformed middling strikeout and walk numbers in 2022 before flipping the script a year ago.

While his ERA jumped nearly two runs between 2022 and ’23, Nelson dramatically increased his strikeout rate and sliced his walk percentage. He has made 11 appearances this year. He opened the season by rattling off eight consecutive scoreless outings before giving up a combined five runs in 1 2/3 frames over his last three games. Nelson will be eligible for arbitration for the first time next offseason.

Arizona has four left-handers in the current bullpen mix: Hughes, Andrew Saalfrank, Joe Mantiply and long man Logan Allen. Hughes and Allen were recent additions to the 40-man roster who might not hold long-term spots, while Saalfrank has spent most of the season in the minors. The Snakes recently snagged grounder specialist Joe Jacques off waivers from the Red Sox and optioned him to Triple-A Reno. Adding a more proven lefty relief arm could be a midseason goal if the D-Backs stick in the playoff mix.