Mariners’ Matt Brash IL Move Pushes Seattle Toward Its Most Intriguing Lefty Depth Piece

The Mariners’ bullpen depth is getting an early test from an unlikely left-handed option.

Sep 27, 2025; Miami, Florida, USA; Miami Marlins pitcher Josh Simpson (66) pitches in the eighth inning New York Mets at loanDepot Park. Mandatory Credit: Jim Rassol-Imagn Images | Jim Rassol-Imagn Images

Matt Brash’s injury update was better than the Mariners had reason to fear, but it still came with a cost. Seattle placed Brash on the 15-day injured list with right lat inflammation, which turned a manageable bullpen concern into something more immediate. The Mariners are not in crisis mode, but they are officially in problem-solving mode. Losing Brash, even temporarily, removes one of their most electric relief arms and leaves the club searching for usable outs in the middle of a long season that does not care much about timing.

The Mariners recalled Josh Simpson from Triple-A Tacoma on Friday, just a few months after acquiring him from the Marlins for cash considerations. At the time, it looked like a classic Seattle margins move: grab an arm with a few interesting ingredients, get him in front of the pitching group, and see whether another organization left something on the table. Now that bet gets a much louder test.

From Justin Hollander: Matt Brash will have 3-5 days of no throw and Mariners will reassess to build him back up. Want to make sure we don’t put him at risk.

— Ryan Divish (@RyanDivish) May 1, 2026

Josh Simpson Recall Puts Mariners Bullpen Depth Under Fresh Pressure

Simpson earned the chance by giving the Mariners something to notice in Tacoma. He allowed just one earned run over 9 1/3 innings with 12 strikeouts before the call-up, which is not enough to declare him the next bullpen find, but it is enough to keep this from feeling like routine roster shuffling. Seattle is not just calling up a fresh arm. It is giving one of its more intriguing left-handed depth pieces a real audition.

His 2025 numbers with Miami were rough. There’s no need to dress that up. He posted a 7.34 ERA and 1.83 WHIP across 30.2 innings with the Marlins, which is the sort of stat line that usually gets a pitcher labeled, boxed up, and moved off the roster without much ceremony.  

Seattle saw something else. Or, at least, saw enough to buy a lottery ticket. This is where the Mariners’ pitching reputation gives the story real substance. Simpson has already been discarded once this year. Miami designated him for assignment, and Seattle pounced. Those moves end up mattering when the season starts taking bites out of the roster.

Simpson gives Seattle a left-handed look, strikeout ability, and a chance to see whether his early Tacoma results can survive better hitters. The appeal is not that he’s a finished product. The appeal is that a lefty who can miss bats is always going to get another chance somewhere, and the Mariners have every reason to believe their pitching infrastructure can help sort through the messy parts.

Seattle is looking to take a pitcher with big-league scars, a useful arsenal, and encouraging Triple-A momentum, then turn him into something functional while the bullpen waits for Brash to heal. That’s a worthwhile gamble.

The Brash injury update could have been much worse. An MRI reportedly showed no serious structural damage, and the issue is lat inflammation rather than the more ominous oblique concern many feared when he exited Wednesday’s game after just two pitches. Still, “not catastrophic” is not the same thing as “problem solved.” Brash is still unavailable. And the Mariners still have innings to cover.