3 aggressive bullpen trades Mariners should execute immediately

With Josh Naylor now in their lineup after last week's trade with the Arizona Diamondbacks, the Seattle Mariners' main priority ahead of Thursday's trade deadline seems to have shifted.

Though Seattle remains engaged on Eugenio Suárez, it's the search for bullpen help that has taken center stage in the last few days. President of baseball operations Jerry Dipoto has spoken openly about wanting to be "aggressive" on the market for high-end relievers, and Adam Jude of The Seattle Times hears from his sources that a late-inning arm is a "more urgent need" than another bat right now.

Ace relievers tend to be overpriced this time of year, but the Mariners have cause to throw caution to the wind. For one, the Houston Astros have recently given them an opening to take control of the AL West. And for two, the Naylor trade barely made a dent in the Mariners' excellent farm system. They still have eight prospects in MLB Pipeline's top 100.

Assuming Dipoto is for real about being aggressive, here are three trade targets he should have his eye on.

3 relievers the Mariners should make aggressive plays for ahead of trade deadline

3. LHP Reid Detmers, Los Angeles Angels

Dan Wilson only has one left-handed option in the bullpen, and that has created some issues. Gabe Speier has too often been needed in low- and medium-leverage spots when he should mostly be working in high-leverage.

Adding literally any competent lefty would solve this problem, but the Mariners might as well aim big. In the case of Reid Detmers, they would stand to get a rising relief star for the rest of 2025 and the next three seasons as well.

The 26-year-old was drafted 10th overall in 2020, but largely failed to live up to his promise as a starter. Now in 2025, his move to the bullpen has unsurprisingly added 1.8 mph to his average fastball, and he's only getting more comfortable. His last 29 appearances have seen him rack up a 1.24 ERA with 40 strikeouts in 29.0 innings.

Detmers is like Speier in that he's no specialist, as he's capable of getting more than three outs as needed. To have not one, but two lefties like that in one pen would be a major advantage.

2. RHP Griffin Jax, Minnesota Twins

The other problem the Mariners have in their bullpen is that there just isn't much in the way of swing-and-miss stuff ahead of Andrés Muñoz. Whereas he's fanning 33.1 percent of the batters he's facing, the pen as a whole is in the bottom 10 of MLB with a 21.5 K%.

Hence the simple appeal of Griffin Jax: He's leading even Muñoz with a 36.9 K%, which ranks seventh among qualified relievers.

The 30-year-old righty runs his fastball at an average of 96.9 mph, but it's really all about his sweeper and changeup. They are his primary pitches, and each has a whiff rate in the 45-50 percent range.

Jax is holding both lefties and righties to a sub-.300 OBP, so there would be no need to use him in a platoon capacity. The Air Force Academy alum would also stick around for two more seasons, as he isn't eligible for free agency until after 2027.

1. RHP Jhoan Duran, Minnesota Twins

Yes, it's another Minnesota Twin. And no, Jhoan Duran doesn't actually strike guys out better than his teammate, Jax. His strikeout rate is "only" 25.7 percent.

But with Emmanuel Clase out of the picture amid a sports-betting investigation, Duran has become the default No. 1 option for all teams in need of bullpen help right now. He has a 2.47 ERA for his career, and that is even though his stuff has yet to be fully unlocked.

The 27-year-old sits at 100.2 mph with his fastball, which ranks behind only Mason Miller (who is more of a speculative trade chip for the Mariners) among qualified relievers. And while he's perhaps best known for his splinker, his knuckle-curve and sweeper actually have better whiff rates.

That is where there may be more to be gained from his arm, and the Mariners are as good a candidate as any team to figure that out. They wouldn't even necessarily have to get the job done in 2025, as Duran is under club control for two more seasons after this one.