Red Sox reliever Wyatt Mills undergoes Tommy John surgery

Injured Red Sox reliever Wyatt Mills underwent successful Tommy John surgery on Wednesday, the club announced. The procedure was performed by Dr. Keith Meister at Texas Metroplex Institute for Sports Medicine & Orthopedic Surgery in Arlington, Texas.

Mills was shut down from throwing in mid-March due to a flexor issue and opened the season on the 15-day injured list with right elbow inflammation as a result. The 28-year-old sidearmer was then transferred to the 60-day injured list on April 16.

Prior to being shut down, though, Mills had shown signs of promise during spring training, striking out 10 of the 32 batters he faced in five Grapefruit League appearances.

Acquired by the Red Sox from the Royals for minor-league reliever Jacob Wallace in December, Mills was originally selected by the Mariners in the third round of the 2017 amateur draft out of Gonzaga. The Washington state native broke in with Seattle in May 2021 and was then dealt to Kansas City last March.

Between the two stops, Mills posted a 4.60 ERA and 3.62 FIP with 26 strikeouts to 13 walks in 27 relief appearances (29 1/3 innings) last season. For his career, the 6-foot-4, 220-pound righty owns a 6.21 ERA in 38 outings (42 innings) at the major-league level.

As noted by MassLive.com’s Christopher Smith, Boston brought in Mills hoping that he could replicate the same sort of success John Schreiber enjoyed out of the Red Sox bullpen last year. Like Schreiber, Mills throws from a similar arm angle and operates with a three-pitch mix that consists of a four-seam fastball, a slider, and a sinker. He had also been planning on adding a changeup to his arsenal, per Smith.

Now, Mills will be sidelined for all of 2023 and most — if not all — of 2024 as well since Tommy John surgery typically takes anywhere between 14 to 18 months to recover from.

Mills, who turns 29 in January, has one minor-league option remaining and is not eligible for salary arbitration until 2026.

Wallace, who turns 25 next month, has pitched to a 3.86 ERA and 4.47 FIP with 31 strikeouts to 20 walks in 28 relief appearances (25 2/3 innings) for the Royals’ Double-A affiliate in Northwest Arkansas so far this season.