Mariners sneak yet another intriguing arm into their pitching program

Seattle has been done making meaningful roster moves for weeks, but that hasn't stopped them from picking up the occasional arm here and there. They've been doing it all winter, stocking up on depth and checking to see if there are any uncut gems hiding out in free agency.

The names they're targeting may be ones you've never heard of. They traded for left-handed pitcher Josh Simpson earlier this week and struck a deal to reunite with Jhonathan Díaz earlier this month. Another recent bullpen addition is as unsuspecting as they come, but could bring at least something to the table.

Seattle signed former Orioles prospect Houston Roth to a minor league deal with plenty to work on

Roth had a decent college career, posting a 3.51 ERA over 123 college innings at Ole Miss, but wasn't taken until the 29th round of the MLB draft by Baltimore. He spent six minor league years in their system and didn't find consistent success until 2024 after being moved to the bullpen.

In 2025, he posted a 3.32 ERA in 40.2 innings in Triple-A but had a concerning 4.75 FIP and 11.6 walk percentage. His path to the big leagues was unclear in Baltimore, especially after being designated for assignment and sent outright to Triple-A, so he elected free agency at the end of the year.

Despite his weaknesses, Roth did some things well. Over the past few years, his strikeout rate was consistently above 30 percent with the exception of his 2025 stint in Triple-A where it was 21.6%.

His most promising weapon is absolutely his sweeper. With average velocity of 83.3 mph and 10.4 inches of glove-side break, it had a chase rate of 42.9 and a 35.6 whiff rate. Like his other pitches, it rarely landed in the zone but its shape was deceptive enough to still be productive.

Unfortunately, that sweeper might be the only promising tool in his kit at the moment. His fastball had an impressive 19 inches of induced vertical break, but with an average velocity in the low-90s and a high arm slot, making the movement more predictable than if he were generating the same backspin from a lower release point. For the most part, his cutter and splitter were waste pitches, rarely landing in the zone and infrequently getting opposing hitters to chase.

As per usual, Seattle's approach to accumulating reliever depth is to seek out underrated arms with at least one redeeming quality. Roth won't be closing out high-leverage games in September for the Mariners, but he's an affordable pitcher that could end up becoming a contributor if the organization manages to make some much-needed improvements. It's a big ask but who knows, anything can happen in baseball.