Mariners expected to be without Trent Thornton for the rest of 2025

The Seattle Mariners’ worst fears were confirmed on Friday, with the news that reliever Trent Thornton had torn his left Achilles.

The mood is extremely good for the Seattle Mariners and their fans right now, thanks to a tremendous trade deadline combined with taking the first two games of their four-game set against the Texas Rangers. However, there was one piece of bad news which emerged on Friday, regarding Trent Thornton.

The Mariners reliever had to leave Thursday night’s series opener versus the Rangers on a cart in the top of the ninth, after falling off the mound while trying to cover first base on a ground ball. Now, after undergoing an MRI it has been confirmed he tore his left Achilles and is not expected to return until next year.

Trent Thornton talks about the aftermath of his injury

Thornton spoke to the media on Thursday following the 6-0 win over the Rangers, to discuss what happened prior to finding out the true severity of his injury. As per Daniel Kramer of MLB.com, he said:

“I tried to get up and just couldn’t even put pressure on it at all It didn’t hurt. It’s just achy and numb. But I guess I don’t know. I’m still trying to process this a little bit.”

Unfortunately for the 31-year-old he will now have plenty of time to process what happened, as he begins his road back to recovery. His injury brings to an end what has been an up-and-down season for him in Seattle.

As a whole there’s no denying Thornton has had his struggles in 2025 as he produced a 4.68 ERA, 4.71 FIP, 1.299 WHIP and -03. fWAR in 42.1 innings over 33 games, which represented his worst returns since 2021. However, since being blasted for five hits and five earned runs in 1.0 innings against the Arizona Diamondbacks on June 11, he had recorded a 2.28 ERA, 2.42 FIP, 1.06 WHIP and 0.4 fWAR in 23.3 innings over 15 appearances.

When the righty first arrived in Seattle in the leadup to the 2023 trade deadline from the Toronto Blue Jays, he had an immediate positive impact. He had a 2.08 ERA, 1.077 WHIP and 0.3 fWAR in 26.0 innings over 23 appearances and became a vital part of the bullpen.

• Dante Fowler Jr Joins Seahawks: A Veteran’s Role
• Mariners do right by Randy Johnson with statue to honor his legacy
• Cal Raleigh’s Injury: Latest News and Prognosis
• Seattle Sounders Struggle with Finishing in Draw
• Seahawks Rookie Mini-Camp Highlights: Key Performers & Insights

How will the Mariners bullpen respond?

Even though Thornton hasn’t been quite as effective ever since, he’s still seen regular use as a reliever and will be missed. The timing of his injury is unfortunate coming post-trade deadline and even though the Mariners did acquire Caleb Ferguson, will have critics asking why they didn’t push more for another reliever, knowing it was a need even before losing Thornton.

There are some bright spots in the bullpen including Andrés Muñoz, Matt Brash and Gabe Speier, but will it prove to be enough moving forward? Ahead of Saturday’s action they rank eight in the majors with a 3.66 ERA, tied-13th with a .240 batting average, 14th with a 1.29 WHIP and tied-18th with 366 strikeouts.

In terms of the roster, Thornton was officially placed on the 15-day Injured List on Friday and righty Jackson Kowar was recalled from Triple-A Tacoma in a corresponding move. Jackson has been effective in limited action this season, with a 1.54 ERA, 0.857 WHIP and 0.3 fWAR in 11.2 innings over nine appearances.

Photos court​‌esy of Tim Rodgers Photography

How comfortable do you feel about the Mariners bullpen following Thornton’s injury? Do you have confidence in their ability to be an effective unit for the remainder of the 2025 season? Let us know in the comments section below.