Mariners claim former Astros reliever Seth Martinez off waivers

The Seattle Mariners continue their quest to improve the bullpen, by claiming the righty off waivers from the Miami Marlins.

Still cognizant of a bullpen which was overworked and running on fumes by the end of the 2024 season, the Seattle Mariners have continued to bring in more relievers to look at. And this time around it is someone who spent the past four seasons pitching for their divisional rivals, the Houston Astros.

As confirmed by the Mariners on social media, they have claimed Seth Martinez from the Miami Marlins and added him to the 40-man roster. Meanwhile, Jackson Kowar has been placed on the 60-day Injured List, which means the 40-man roster remains full at 40 players.

During his four seasons in the Majors with the Astros, Martinez pitched a combined 137.1 innings over 111 appearances out of the bullpen. In the process he produced a 3.93 ERA, 4.24 FIP and 1.303 WHIP, with a 20.7 strikeout rate and 9.2 walk rate.

Improved reliability by Seth Martinez last season

Last season was a solid one for the 30-year-old, as he had personal Major League bests of 44 appearances and 52.2 innings. He recorded a 3.59 ERA and 1.272 WHIP, although he did also produce a career-high — albeit not disastrous — 4.78 FIP.

After the 2024 season concluded, the Astros designated Martinez for assignment and he was subsequently claimed by the Arizona Diamondbacks. The same fate then awaited him as he was then claimed by the Marlins before ending up in Seattle, with the sequence of events somewhat influenced by now being out of minor league options.

If the Peoria, Arizona native can stick around with the Mariners organization, he could prove to be useful. In fact, for what it’s worth, FanGraphs‘ ZIPS projections have him pitching a career-high 58.0 innings in 2025 and producing a 3.88 EA and 4.20 FIP, although a 1.330 WHIP doesn’t look quite as appealing.

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Mariners bullpen has the potential to be special

Again assuming Martinez stays with the Mariners, his pitching arsenal sees him mostly utilizing a four-seamer fastball and sweeper. In addition though, he does also throw a sinker and changeup.

Irrespective of Martinez’s fate, the Mariners will be banking on the return of Matt Brash after a full season out, along with more innings from Gregory Santos. The overall stats last season show the M’s have the ability to be one of the better bullpens in the Majors this year, but only if they have more contributors and not have to rely on Andrés Muñoz as much.

As for Kowar, he underwent Tommy John surgery last March, and with the move to the 60-day Injured List, the earliest he can play again is towards the end of May. He has yet to pitch for the Mariners in the Majors, after arriving in Seattle as part of the return package which sent Jarred Kelenic, Marco Gonzales and Evan White to the Atlanta Braves.

What do you predict Matinez will bring to the Seattle Mariners, assuming he sticks around? Further, what kind of success do you expect from the bullpen in general this coming season? Let us know in the comments section below.