Mariners non-tender cuts close the book on a truly disappointing trade bust

The non-tender deadline came and went on Friday night, and the Seattle Mariners chose to part ways with a trio of relievers who had been eligible for arbitration: Gregory Santos, Trent Thornton and Taylor Saucedo.

Saucedo had already been designated for assignment, so he was a sure goner going into Friday. Thornton, however, seemed to have a chance of being brought back to provide bulk innings after finishing his recovery from a torn Achilles tendon — which could still happen if he and the Mariners can work something out.

As for Santos, it says a lot that the Mariners didn't think he was worth even a projected $800,000 salary, or barely more than the MLB minimum for next season. His tenure in Seattle was that bad, and it truly sucks to say as much knowing that he arrived with so much promise.

Mariners close the book on a truly disappointing trade bust by non-tendering Gregory Santos

It was in February of 2024 that the Mariners acquired Santos from the Chicago White Sox. They gave up Prelander Berroa, Zach DeLoach and a competitive balance pick, all for a controllable reliever — Santos wasn't slated to become a free agent until after 2028 — with an exciting profile.

Santos had appeared in 60 games for the White Sox in 2023, and he was harder to hit than even his 3.39 ERA let on. He fanned 66 batters in 66.1 innings and allowed only two home runs to the 289 batters he faced. His slider had a whiff rate of 37.5 percent, and his sinker had devilish movement even at 101 mph.

Going into the 2024 season, Santos looked like the right guy to form a dominant back-end trio in the Mariners' bullpen. It was meant to be him and Andrés Muñoz and Matt Brash, the latter two of whom had each fanned upwards of 12 batters per nine innings in 2023.

Yet this was always contingent on Santos staying healthy, which was uncertain from the get-go after his 2023 season had ended early because of an elbow injury. And rather than go away, the hits just kept on coming in Santos' two years in the Mariners organization. Problems with his lat, knee and biceps rendered him barely able to pitch at all, as he made a total of 30 appearances in the minors and majors across 2024 and 2025.

The eight appearances that Santos made for the Mariners this year were painful to watch. He faced 36 hitters and gave up six hits and eight walks, and he didn't strike out a single one of them. He was optioned to Triple-A Tacoma after he made a mockery of a close game in Cincinnati on April 15. As of now, that still stands as his last appearance in the majors.

Santos is still only 26 years old, so it won't be surprising if an MLB organization takes a flier on him as a reclamation project. It just probably won't be the Mariners. When a team is spooked by even an $800,000 salary, it tells us that it doesn't think the very real risk of a low floor is worth the far-flung reward of a high ceiling.