The Mariners’ big league club may be spinning its wheels, but the pipeline underneath it is moving fast. With Lazaro Montes and Michael Arroyo already ticketed for Triple-A Tacoma after strong runs at Double-A Arkansas, attention naturally shifts to the next wave of names knocking on the door.
Seattle has a few obvious candidates, and the organization’s current crop points to two pitchers and a shortstop as the likeliest to get the next bump.
Left-hander Mason Peters has made a strong first impression in pro ball. The fourth-round pick out of Dallas Baptist University in last year’s draft has logged 44.2 innings over 11 starts for Single-A Inland Empire and turned in a 1.41 ERA with a 3.14 FIP.
His strikeout and walk numbers stand out too: a 37.1% strikeout rate against a 4.7% walk rate. That kind of mix suggests he’s not just missing bats, but also working ahead and putting himself in good counts.
Peters has spent the whole season in Single-A, and the next step looks close. The source of caution is workload and experience - he didn’t pile up many college innings, so jumping him straight to Double-A would be aggressive. A move to High-A would still raise the bar without pushing too hard, and it could be the right kind of test for a pitcher who’s already handled his first pro assignment with ease.
Shortstop Felnin Celesten is another name in the mix after a rebound season. 2025 didn’t go the way he wanted, but 2026 has been a different story at High-A Everett. Through 337 plate appearances, he’s posted a 138 wRC+ with 12 home runs.
His strikeout rate sits at 20.2%, the lowest it’s been since his Arizona Complex League days, and his power has taken a real jump too - his ISO has climbed from .099 in Single-A last year to .213 this season. He’s also swiped 17 bases, helped by getting on base more often.
Celesten’s path to Seattle isn’t as clean as some others because Colt Emerson is there and Cole Young has surged back into the picture. Even so, the Mariners could still decide a promotion makes sense if it boosts Celesten’s trade value ahead of the deadline or later in the offseason.
Then there’s Kade Anderson, the club’s top prospect and the No. 5 overall prospect. The Mariners have made it clear they intend to move him up.
His Double-A numbers leave little room for debate: a 1.36 ERA and 1.84 FIP over 72.2 innings. He’s been too good for the level, and the only real question now is where he fits.
The problem is roster space. Seattle doesn’t have an obvious opening for him right now.
Some think the Mariners could use him out of the bullpen. Others believe the team might trade from its rotation depth to clear a lane.
But the expectation is the same either way: Anderson is coming. It’s just a matter of when.
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