Oakland Athletics starting pitcher Ken Waldichuk. Robert Edwards-USA TODAY Sports

The Athletics announced Friday that left-hander Ken Waldichuk has quietly been going through a non-surgical rehab process after being diagnosed with a strained left flexor tendon and sprained ulnar collateral ligament in his left elbow. Waldichuk experienced discomfort in his final appearance of the 2023 season, according to the team.

“Waldichuk opted for conservative treatment of this injury, leading to a Tenex procedure with Dr. Steve Yoon on Oct. 17 and a follow-up [platelet-rich plasma] injection to the flexor tendon on Oct. 24,” the team announced in a statement. “Waldichuk is currently in physical therapy; his timeline for returning to throwing remains TBD.”

The Tenex procedure that Waldichuk underwent is rare but not unheard of among pitchers. Veteran right-hander Collin McHugh had the same treatment in the 2019-20 offseason. He wound up not pitching that year, opting out of the pandemic-shortened campaign and citing that he hadn’t recovered from his offseason procedure as well as hoped. Of course, every injury situation is different, and the fact that McHugh didn’t return in 2020 is hardly an indication that Waldichuk will face similar problems. Furthermore, McHugh returned to the mound in 2021 without undergoing further treatment and has been healthy since. Over the past three seasons, he’s compiled 192 innings with a strong 2.77 earned run average.

Waldichuk, 25, came to the A’s from the Yankees before the 2022 trade deadline as part of the return package for right-handers Frankie Montas and Lou Trivino. The hope was that he’d provide Oakland with a largely MLB-ready starting pitcher to help replenish a staff that had been thinned out by injuries and trades during the team’s latest rebuild. Waldichuk has struggled throughout his time in Oakland, however.

A 2019 fifth-round pick, Waldichuk made his MLB debut with the A’s in 2022, starting seven games down the stretch and turning in a pedestrian 4.93 ERA — albeit with solid strikeout and walk rates of 22.6% and 6.8%. The 2023 season was another story entirely, as Waldichuk’s struggles eventually led the team to move him to the bullpen. The southpaw returned to the rotation around the All-Star break and pitched decently down as a starter in the second half, logging a 4.04 ERA with a 21.8% strikeout rate and 9.2% walk rate. His overall 2023 numbers were still unsightly (5.36 ERA, 20.7% strikeout rate, 11.1% walk rate, 1.53 HR/9), but Waldichuk ended the season on a relatively high note and looked to have turned a corner.

The revelation of a notable arm injury throws a wrench into his near-term outlook, however. Waldichuk had been one of the leading candidates to pitch out of the Athletics’ rotation next year, joining Paul Blackburn, JP Sears and prospect Mason Miller in that regard. Other candidates include Luis Medina, Adrian Martinez, Freddy Tarnok, Joey Estes and Osvaldo Bido, though the Oakland rotation mix on the whole is generally comprised of unproven arms. Sears and Blackburn are the only two who’ve had even a full season of average or better results, and Blackburn could be traded this offseason given that he only has two years of club control remaining.

Waldichuk’s injury is a blow to the group and to his broader development as a big-league starter, though even if he winds up missing significant time he could still be a part of the Athletics’ long-term plans. The lefty has one-plus year of Major League service time, so he can be controlled another five years. He also still has all three minor league option years intact, although since the injury occurred while pitching in a big league game, he’d very likely be placed on the MLB injured list to begin the year (if an IL placement proves necessary), during which he’d earn service time as well.

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