5 Mariners trade chips whose value is trending up ahead of the deadline

It took a while, but the Seattle Mariners have cemented themselves as trade season buyers with their recent play. But that's just one question concerning the club's approach to the August 3 trade deadline, with the other being which players they might be willing to part with.

It should be a long list. The Mariners have some redundancies on their major league roster. They also have arguably the AL's best farm system, with Colt Emerson and Kade Anderson standing out as the only true untouchables.

So, here's the big question: Of the potential trade chips in Seattle's inventory, which ones are gaining in value?

2 Mariners players who could be trade chips

It's no secret that the Mariners have more starting pitchers than they have room for, and that's without Anderson just yet. Once Brendan Donovan returns, they're also going to have more left-handed hitters than they have everyday roles for.

DH/OF Dominic Canzone

Canzone's rise in 2025 seemed to come out of nowhere, and that wasn't the only reason to wonder if this year would prove it was too good to be true. The 28-year-old crashed out in last year's playoffs, going 3-or-28 with no extra-base hits in 11 games.

Well, so much for that. Canzone's 136 OPS+ basically mirrors the 139 OPS+ he had last year, and he's come out of a lull with six extra-base hits in his last nine games. It would be hard for most teams to part with a hitter with these creds, but not the Mariners. Trading Canzone, who's under club control through 2029, would allow Donovan and Luke Raley to share right field and DH.

RHP Luis Castillo

Even if there isn't technically an odd man out in Seattle's starting rotation, Castillo comes the closest. He's come out of the bullpen in two of the club's three uses of the piggyback with Bryce Miller, and a more permanent role in that capacity might be the best thing for him.

Credit where it's due, though, the 33-year-old has allowed only three earned runs in 11.1 innings in his three piggyback assignments. It's a small sample size, and it doesn't lesson the righty's $24.15 million salaries for 2026 and 2027. Even so, it could be enough to get pitching-needy teams to call the Mariners about him.

3 Mariners prospects who could be trade chips

The Mariners aren't short on attractive prospects outside of Emerson and Anderson, but not all of them are trending upward. It's been a weird year for Michael Arroyo and Jonny Farmelo, while Luke Stevenson really hit the skids in May.

SS Felnin Celesten

Celesten, of course, did not hit the skids in May. He had a 25-game hit streak at one point, and he ended the month with a .352/.460/.538 slash line. He just crept into MLB Pipeline's top 100, and The Athletic even has him in the top 20.

Celesten fits the description of the kind of prospect Jerry Dipoto would sell high on. As he's obviously talented, but still very young (he only turns 21 on September 15) and far from the majors at High-A, there's a slight resemblance to Noelvi Marte in 2022.

OF Lazaro Montes

Montes is such a polarizing prospect that it's somewhat surprising that he's broadly regarded as a top-100 talent. The power is there in spades and he walks plenty, but the swing-and-miss and subpar athleticism give him a profile as a boom-or-bust major leaguer.

All the same, the 21-year-old's name came up during the Donovan trade negotiations with the St. Louis Cardinals over the winter. His "boom" potential thus interests at least one team, and there could be more after he recovered from a slow April by blasting nine home runs for Double-A Arkansas in May.

RHP Ryan Sloan

No, we don't think the Mariners are keen on trading Sloan. The 20-year-old is considered by some to be an even better pitching prospect than Anderson. He's also hot, as six perfect innings his last time out lowered his ERA for his last four starts for Arkansas to 1.83 — and that's with 29 strikeouts and only one walk.

Even so, Sloan is the button the Mariners might have to push if they get a chance to make a mega-blockbuster trade. As unlikely as both names might sound, we're talking a deal for a Tarik Skubal or a Yordan Alvarez. You know, true "World Series or bust" stuff.

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