Seattle Mariners reliever Trent Thornton clutches his ankle during a game against the Texas Rangers on July 31 at T-Mobile Park. Steven Bisig-Imagn Images

Seattle Mariners Right-Handed Reliever Tears Left Achilles, Placed on Injured List

Originally posted on Seattle Mariners on SI
By Teren Kowatsch | Last updated Aug 1, 2025 6:15 PM ET

SEATTLE — One of the Seattle most often-used relievers will be on the injured list for an extended period of time.

In a 6-0 win against the Texas Rangers on Thursday, Mariners right-hander Trent Thornton stumbled off the mound while attempting to cover first base on an infield single in the top of the ninth.

Thornton clutched his left ankle after falling and briefly tried to stand before laying back down on the grass. He was checked on by trainers and was eventually carted off the field.

Seattle confirmed the injury was a torn left achilles tendon and placed him on the 15-day injured list Friday. The club recalled right-handed reliever Jackson Kowar from the Triple-A Tacoma Rainiers in a corresponding move.

Roster moves:

Jackson Kowar, RHP, recalled from Triple-A Tacoma.
Trent Thornton, RHP, placed on 15-day Injured list (torn left Achilles).

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— Mariners PR (@MarinersPR) August 1, 2025

Thornton was acquired by the Mariners back in 2023 and has been one of the most dependable bullpen arms for the team since.

Thornton has posted a 3.65 ERA with 130 strikeouts across 140.2 innings pitched in 127 outings with the team since 2023. He has a 4.68 ERA and has fanned 32 batters in 42.1 innings across 33 outings with the club this season.

Thornton was previously on the IL for nearly a month this season. He was on the shelf from May 9-June 7 due to surgery for appendicitis.

Kowar made his team debut for Seattle this season. He was activated from the IL May 28. He was acquired by the Mariners in a trade with the Atlanta Braves on Dec. 3, 2023, but was out all of 2024 recovering from Tommy John surgery.

Kowar has a 1.54 ERA with nine strikeouts in 11.2 innings pitched across nine outings with the Mariners.

This article first appeared on Seattle Mariners on SI and was syndicated with permission.

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