Oct 15, 2025; Seattle, Washington, USA; Seattle Mariners pitcher George Kirby (68) throws in the first inning during game three of the ALCS round for the 2025 MLB playoffs at T-Mobile Park. Mandatory Credit: John Froschauer-Imagn Images John Froschauer-Imagn Images

Mariners Sign 29-Year-Old Righty Away From Phillies

Originally posted on Fastball on SI | By Jackson Roberts | Last updated Jan 24, 2026 5:00 PM ET

The Seattle Mariners have one of the best pitching labs in the majors, and if you ever make it to the major league team, you get to play in a ballpark known to suppress offense.

With those factors in mind, it makes sense that a minor-league free agent would want to land with the Mariners if they got the chance. This offseason, 29-year-old right-hander Gabe Mosser got that chance and took it.

According to the transactions log on his official roster page, Mosser signed a minor-league contract with the Mariners on Jan. 16. The deal took an additional week to show up on the log, which is not unusual at this time of year.

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What Mariners are getting in Gabe Mosser

Mosser, a Philadelphia-area native, just spent the past season playing in his hometown Philadelphia Phillies organization. He'd previously been a 27th-round pick in 2018 and spent six seasons in the San Diego Padres organization.

In 25 starts this past season, split between Double-A and Triple-A, Mosser posted a 5.20 ERA in 124 2/3 innings. He struck out 127 batters, so that was a plus, but he gave up 127 hits as well, while walking 49 batters.

The Mariners assigned Mosser to Triple-A Tacoma, though that's not set in stone, and it seems as though he'll be a safe bet to eat innings. That alone is valuable to an organization, especially at Triple-A, where players are constantly being sent up and down as injuries and trades occur.

However, if Mosser wants to get himself to the majors this year, he'll have to come out of the gates blazing, and prove he can keep hard contact down while cutting into his walk rate a bit as well.

It's not a signing that Mariners fans are guaranteed to remember for years to come, but Mosser could be a valuable piece this season in a few ways, and one never knows when a minor-leaguer might be due for a breakout.

More MLB: Mariners, Mets Complete Trade Bringing 5-Year MLB Veteran to Seattle

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

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