3 Mariners top prospects next in call-up line after Lazaro Montes, Michael Arroyo

If you can't be good, at least be interesting. And since the Seattle Mariners seem incapable of checking the first box, you have to hand it to them for checking the second by calling up Kade Anderson, Lazaro Montes and Michael Arroyo all within two weeks of each other.

So, who's next? And when?

Perhaps it's greedy to ask this question. Before there was Anderson, Montes and Arroyo in the big leagues, there was also Colt Emerson. That's one, two, three, four top-100 prospects to debut for the Mariners in a single season, which is not something that happens every year.

Yet since the Mariners still have a top-heavy farm system that features prospects who are starring in the high minors, it's worth looking closely at three players (plus a wild card!) who are next in line for promotions.

Ryan Sloan should be next to make his Mariners debut, but keep an eye on Boston Smith and Jonny Farmelo

Ryan Sloan, RHP

MLB Pipeline Mariners Rank: No. 2
Current Level: Double-A
MLB ETA: Early 2027

Though the season is running out of time, it may not be wise to rule out Ryan Sloan making his Mariners debut before 2026 is over. Seattle prospects jumping from Double-A to the majors is sort of a rite of passage, even if it does mean adjusting to a different ball.

Though Sloan is only 20 years old, he already resembles a dream pitching prospect. He's a sturdy 6-foot-5, 220 pounds. He throws up to 100 mph with a nasty sweeper. And best of all, he absolutely pounds the strike zone.

It's been a tale of two seasons for Sloan this year, and it's the second one that really gets at why Mariners fans should be hyped for his arrival. He began this year with a 5.09 ERA and an .802 OPS allowed through 10 starts. His last 11 starts have yielded a 2.70 ERA with a .585 OPS, as well as 73 strikeouts against just three walks. Yes, three walks.

Boston Smith, C/LF/DH

MLB Pipeline Mariners Rank: No. 13
Current Level: Double-A
MLB ETA: Mid 2027

Boston Smith has only been in the Mariners' farm system for a few weeks, having come over in the Luis Castillo trade with the Chicago White Sox. He didn't look like the centerpiece then. He does now.

Nobody could have seen 2026 coming when the Washington Nationals made Smith a sixth-round pick in the 2025 draft. He's been one of the best hitters in the minor leagues, batting .274/.430/.578 with 31 home runs. His 162 wRC+ is tied for second among all MiLB hitters with at least 450 plate appearances.

Where Smith fits defensively is still a major unknown, but the Mariners have every excuse to lean into expediting the arrival of his bat. If that means giving him more time in left field to begin next year, so be it. Either way, he'll be on the doorstep to the majors if he begins next year at Triple-A.

Jonny Farmelo, CF

MLB Pipeline Mariners Rank: No. 6
Current Level: Double-A
MLB ETA: Late 2027

Jonny Farmelo got promoted to Double-A at the same time as Felnin Celesten, who is generally regarded as the better prospect of the two. Yet that's when the wheels came off Celesten's season, as he posted just a .507 OPS in 31 games with Arkansas before he was shut down with a groin injury.

For his part, Farmelo has been healthy enough to play in 124 games after injuries limited him to only 75 games in 2024 and 2025. He's also been productive, to the tune of an .810 OPS, 15 home runs and 40 stolen bases.

A downturn at Double-A to a .697 OPS has slowed the speedy Farmelo's advance, but he's still garnering attention as a prospect worth watching. He could be in line for the Montes/Arroyo treatment around this time next year, and maybe even sooner if he comes out hot.

Ace Reese is already testing how quickly the Mariners are willing to move a prospect

Ace Reese, 3B

MLB Pipeline Mariners Rank: No. 8
Current Level: Single-A
MLB ETA: Early 2028?

To be clear, we're not so much counting Ace Reese as gesturing emphatically in his direction. He's only a few weeks removed from being drafted at No. 24 overall, yet to say he's made a good first impression would be understating it.

Reese has played in 21 games with Inland Empire and batted .440/.530/.667 with eight doubles and three home runs. He's also walked 19 times and struck out only 12 times. Put simply, he's been too good for the competition he's faced.

As Reese was also a standout hitter at Mississippi State, there's already a bit of a Nick Kurtz vibe at play here. It's unfair to expect Reese to keep moving that fast, but it's to his credit that he even has us thinking about it.

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