Mariners pitcher to undergo Tommy John surgery

The Mariners announced that right-hander Jackson Kowar has been placed on the 60-day injured list due to a tear in his right UCL. 

General manager Justin Hollander told reporters (including Ryan Divish of The Seattle Times) that Kowar will undergo Tommy John surgery next week, so the righty will now be out of action until around the midpoint of the 2025 season. The 60-day IL placement for Kowar creates a 40-man roster spot for Ryne Stanek, whose signing is now official.

It’s a brutal setback for Kowar, who went into 2024 looking for a fresh start.  The Royals selected Kowar 33rd overall in the 2018 draft and viewed the righty as one of several young arms that would help spur the organization’s next contention window.  

Unfortunately, Kowar (and essentially all of Kansas City’s pitchers to date) has yet to show much in the big leagues, with only a 9.12 ERA to show for 74 innings over the last three seasons.

Kowar made eight starts in his 2021 debut season but has since worked only as a reliever in the majors.  The move to the bullpen upped his fastball velocity but not much else, as batters have continued to tee off on Kowar’s offerings. Shaky control has also been detrimental to Kowar’s cause, with a 13.7 percent walk rate and a modest 20.1 percent strikeout rate.

The Royals opted to move on from Kowar in November when he was traded to the Braves for Kyle Wright. Kowar’s stay in Atlanta lasted just a couple of weeks as he was flipped to the Mariners as part of the five-player trade that brought Jarred Kelenic to Atlanta.  

From Seattle’s perspective, the trade moved a good deal of salary off the books at the cost of Kelenic, and the M’s got to pick up a couple of younger arms in Kowar and Cole Phillips, a second-round pick from the 2022 draft. 

Unfortunately, Phillips was already recovering from a TJ surgery and recently had to undergo a second procedure, while Kowar has now also been sidelined with the same surgery.

News surfaced earlier this week about a possible arm injury for Kowar, adding to a list of reliever injuries Seattle has already had to address this spring.  

Gregory Santos has been dealing with soreness in his teres major area but is back throwing bullpen sessions, while Hollander also said that Matt Brash is upping his games of catch to throws of 90 feet.  

Brash was recently given the green light to start throwing again after a bout of elbow inflammation, as it appeared as though he dodged what initially appeared to be a much more serious injury.  

Given all these health concerns, it isn’t surprising the Mariners felt the need to spend $4M on Stanek to reinforce the relief corps.