6 positive Mariners farm system developments you might have missed amid 2026 chaos

It's only getting harder to spin the Seattle Mariners' 2026 season in a positive way. They're 10 games under .500 with 12 left to play. If there's a pig out there that looks good in lipstick, this ain't it.

Thank goodness that the farm system is an ever-present silver lining during the Jerry Dipoto era. And this has been a big year for said farm, which has graduated four top-100 prospects to the major leagues: Colt Emerson, Kade Anderson, Lazaro Montes and Michael Arroyo.

Even with those four players having made it to the majors, the Mariners are still rich in talent down on the farm. And at least when it comes to the players that matter the most, there was no backsliding this year. Pretty much everyone made forward momentum.

These 6 prospect storylines allow the Mariners to salvage something from 2026

Ryan Sloan found his footing

A 2026 call-up once seemed possible for Ryan Sloan, but Dipoto shot that down last week when he clarified that the 20-year-old right-hander is going to finish his year with Double-A Arkansas. His major league debut will have to wait until 2027.

Sloan didn't help his cause by getting off to a slow start, as his ERA after 10 outings stood at 5.09. Yet he more than steadied the ship over his next 12 starts, putting up a 2.82 ERA and striking out 77 batters against just five walks in 60.2 innings.

Along the way, Sloan stopped by the Futures Game and showed off his 100 mph fastball. Depending on who you ask, that isn't even his best quality. He also boasts a plus slider and changeup and uncommonly good command for prospect who's just two years out of high school.

Jonny Farmelo and Felin Celesten stayed healthy and broke out

These two entered 2026 as well-regarded prospects who had a common asterisk. After going to the Mariners with the No. 29 pick in the 2023 draft, Farmelo was limited by injuries to just 75 games across 2024 and 2025. For his part, Felnin Celesten got into just 136 games in 2024 and 2025 after the Mariners signed him to a $4.7 million bonus in 2023.

Farmelo has completely flipped the script. He's played in 129 total games between High-A Everett and Double-A Arkansas, and put up an .811 OPS with 17 home runs and 41 stolen bases. The outfielder's production has slowed (i.e., .713 OPS) since he got to Arkansas, but the usual caveat applies: Dickey-Stephens Park is hell on hitters.

Unfortunately, Celesten's season came to an early end because a groin injury. It is nonetheless considered minor, and he was able to get into 111 games with Everett and Arkansas before it happened. He played slick defense at shortstop and posted an .822 OPS, altogether making a case for himself as one of MLB's very best prospects.

Luke Stevenson built on his strong debut

Luke Stevenson dropped like a bomb after the Mariners made him the No. 35 pick in the 2025 draft. He got into 22 games with Single-A Modesto and racked up an impressive .460 on-base percentage.

This year has been more of the same in that regard, as Stevenson has gotten on base at a .405 clip with High-A Everett. Even better, he's showed off more power in cranking 22 home runs. The catch is that he's also run up a 29.3 K%, but you can still see him as fitting the same model of a patient, slugging catcher with legit defensive chops that has made Cal Raleigh a star.

Raleigh is signed through 2030. Stevenson is on a 2028 trajectory. It's not a collision course just yet, but it's definitely some kind of course that has our attention.

Ace Reese hit the ground running

Speaking of strong first impressions, Ace Reese is already causing us to rethink his major league timeline just weeks after the Mariners chose him 24th overall in the draft.

The Mariners flaunted him as an elite hitter at the time, and he's lived up to the billing in the 22 games he's played with Single-A Inland Empire. He has a 1.197 OPS, with more walks than strikeouts and 11 extra-base hits. He also just looks hitterish up there.

Whereas Stevenson is a catcher all the way, the question Reese must answer is whether he can hack it as an everyday third baseman. The jury's out in this regard, but the Mariners are no doubt crossing their fingers. They could use some long-term hope at the hot corner.

Mason Peters revealed himself as a hidden gem

Mason Peters was the second left-hander the Mariners chose in the 2025 draft, and he was a bit less hyped than the first. Whereas Kade Anderson went No. 3 overall, Peters didn't come off the board until the fourth round.

Cut to now, though, and his first 18 starts for Inland Empire and Everett have yielded a 2.10 ERA with 87 strikeouts and 19 walks over 64.1 innings. He's allowed a .182 batting average, the 24th-lowest out of 945 minor league pitchers with at least 60 innings pitched.

If anyone's not already privy to it, Peters has one of the prettiest curveballs of any pitching prospect in baseball today. Even if he doesn't make it as a starter, that pitch could be a weapon in a relief role.

Boston Smith already looks like a steal

To be honest, we weren't familiar with Boston Smith when the Mariners acquired him from the Chicago White Sox in the Luis Castillo trade. It took a minute before we had the realization: "Wait a second, this dude has a 1.038 OPS!"

That OPS has since fallen to .990, but that was to be expected after he joined Arkansas and had to play games at DSP. He's still an exciting hitter, with creds that include a 1.031 OPS in left-on-left matchups and a pull-heavy approach that feels modern in a good way.

A bat like this might be too good to waste at catcher, and doubly so given that Smith isn't the best catcher out there. A future in left field might be the way to go.

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