3 Mariners who'll survive on the roster past the trade deadline, but shouldn't

Roster construction in baseball is far from easy. There are so many moving parts and player performance is often inconsistent given the sheer difficulty of the sport. Once you throw in contractual obligations and the complex nuances of trade negotiations, organizations sometimes end up with a few guys whose roster spots would be better occupied by someone else.

For the Seattle Mariners, despite some players managing to exceed expectations, there are a handful of players that they'd love to get off of their payroll given their slumping numbers. Unfortunately, it's difficult to find willing buyers for these names which will probably keep them around a little while longer.

The Mariners should move on from these 3 players, but likely won't

RHP Trent Thornton

Last year, Thornton was a decent setup option with a 3.61 ERA and 3.47 FIP. He had a wider arsenal than most relievers, which allowed him to keep opposing batters on their toes. His sweeper and slider were by far his most effective pitches.

This year, he has struggled to be consistent, as illustrated by his 5.53 ERA and 6.31 FIP. Despite finding success with his breaking balls in 2024, he has prioritized his four-seam fastball and cutter this year, resulting in more contact. He also dealt with a somewhat uncommon injury that sent him to the injured list, so his year has already been full of ups and downs.

On one hand, Thornton is a cheap arm that has demonstrated the ability to be an effective piece of the bullpen. On the other hand, it's clear that he needs some work before he returns back to his peak form and it's somewhat doubtful he'll garner enough value to bring a real impact piece to Seattle.

INF/OF Dylan Moore

After a career-best year in 2024 where he posted 2.2 rWAR and won a Gold Glove for his utility efforts, the future seemed bright for Moore. Unfortunately, he has been less than stellar this season after cooling off from his scorching start. He had a .682 OPS in May and a .127 OPS in June as he gradually saw his playing time decrease, ceding more time to Cole Young and Miles Mastrobuoni.

Defensively, he has been solid at second base with four Defensive Runs Saved, but his rapidly declining offensive output makes him a potential liability in the lineup. There may be a chance that a team has a very specific need for a player who can play almost any position on the field, but it'd be tricky to find an organization whose need outweighs his lack of presence at the plate.

Furthermore, he'll be a free agent this winter, so he wouldn't be more than a rental option. In between a rock and a hard place, he's neither impactful enough to be picked up by a contender nor under enough team control to be appealing to a rebuilding organization.

DH Jorge Polanco

In many ways, Polanco's decline has been an even more extreme version of Moore's. At one point, he had a better offensive profile than Aaron Judge, but those days are long gone. After a .413 OPS in May and a .582 OPS in June, his OPS+ has regressed to near average levels and the skid doesn't seem to be slowing down any time soon.

We know that when he runs into these cold streaks, it's often due to recurring injuries and this case seems no different. Regardless of the underlying cause behind his recent struggles, he'll be a hard player to market under the current circumstances.

Polanco has a mutual option for 2026 which more than likely means he'll hit free agency after the conclusion of this season, giving a potential new suitor no real use for him in the final months of the season. Things could change if he returns to the Polanco we saw in April, but there hasn't been any indication of that in months.