The Mariners can promote all the young talent they want. Eventually, somebody will have to claim a job. Their 2027 youth movement will be more interesting than the next round of prospect rankings. Kade Anderson, Lazaro Montes and Michael Arroyo have already reached the majors. Ryan Sloan seems to be the logical choice of who could be next. And we do have two more intriguing names behind them.
Colt Emerson, who only recently graduated from prospect status and will enter 2027 returning from season-ending wrist surgery. He technically no longer qualifies for this list, but we can’t pretend he’s remotely close to an established major leaguer after 69 games.
The organization has already supplied some introductions. They just need to determine which young players can handle bigger roles on a team that should be trying to win now.
Mariners Prospects Who Could Earn Major Roles in 2027
Kade Anderson, LHP
Anderson is by far the easiest projection on the list because it hardly feels like a projection anymore. The lefty dominated Double-A, reached Seattle in August and finished his seven-start debut with a 3.79 ERA over 35 2/3 innings. A 103.8 mph comebacker ended his final appearance early, but initial X-rays were negative and the diagnosis was only a forearm bruise.
Assuming nothing comes of it and his offseason proceeds normally, Anderson should enter camp with a rotation job waiting for him. His combination of command, a devastating changeup and four usable pitches gives him more than one way to get through the order, something that takes a while for a lot of young arms to possess.
One of the biggest obstacles may be the workload. Anderson threw 129 innings between Arkansas and Seattle after pitching 119 innings for LSU in 2025. We’re unsure if the Mariners are going to approach 2027 with a pitch count for Anderson. But like most young arms, there will probably be some guardrails to preserve him for his first full major league season.
There's no question about whether Anderson belongs. It’s just how much can he give them next season.
Lazaro Montes, OF/DH
The opening is Montes’ to claim, or surrender. The left-handed slugger homered in his major-league debut and showed enough raw power during September (.212/.305/.481, 4 home runs, 11 RBI) to make everyone in the ballpark pay attention. That power is real, and no section of the stadium appears safe from receiving a souvenir. The opportunity he has is just as real.
Montes offers a chance to end some of the Mariners lineup shuffling. If he hits, he belongs in right field or at DH and somewhere near the middle of the order. His obstacle is considerably more complicated than cutting out the strikeouts. He must prove that he can’t be neutralized by major-league pitchers with breaking balls outside the zone and velocity in uncomfortable locations. His defense also has to remain playable enough that the Mariners aren’t forced to hide him at DH every night.
Michael Arroyo, INF/OF
The utility label can be helpful, sometimes. With Arroyo, it could be a trap because they don’t know where to put him. He reached the majors in September and collected 13 hits in 35 at-bats. He controls the strike zone, makes contact and can move around the diamond.
The Mariners should resist making “moves around the diamond” his entire identity. He could get lost in the shuffle. He has a realistic path to spelling Cole Young at second base, sharing time with Brendan Donovan at third base or occupying a corner outfield spot. Positional flexibility can get him into the lineup, but the bat has to keep him there. If he continues producing, Seattle should identify his best defensive home and let him settle into a regular role.
The obstacle is roster congestion. Emerson, Young and other young players need infield opportunities, while Seattle could still add an established bat from outside the organization. Arroyo will have to outperform the club’s temptation to treat him as a convenient bench piece.
Ryan Sloan, RHP
Sloan is the player most likely to turn this list into an argument. MLB Pipeline currently gives him a 2028 estimated arrival, and he hasn’t pitched above Double-A. That’s not uncommon when it comes to the Mariners. But still, they have enough arms that make any guaranteed 2027 rotation assignment far too aggressive.
However, it’s still not unrealistic. Sloan posted a 3.50 ERA with 117 strikeouts and only 14 walks through his first 20 starts for Arkansas. His fastball-changeup combination and somewhat solid control give him the foundation to move quickly once Seattle decides his workload is ready for another jump.
His path is interesting though. Unless the Mariners move another starter or lose one to injury, the probability for Sloan may actually run through Triple-A Tacoma before the majors.
The Mariners shouldn’t need to rush him. Their rotation already includes established starters, with Anderson attempting to secure his own place. Sloan will have to create an opening with performance rather than prospect hype.
Recent Mariners Prospect Graduate Colt Emerson Faces a Crucial 2027
Emerson is no longer a prospect. Still, he’s only 21 years old, has played 69 major-league games and will enter 2027 coming off surgery to repair a displaced tendon in his left wrist. With that context, we’re going to include him in the conversation.
He hit eight home runs during his rookie season, but his production fell off badly after an encouraging start. The wrist provides important context. Seattle knew the injury was lingering, although the club didn’t initially understand how much it was affecting him. The Mariners ultimately shut him down in August, and general manager Justin Hollander said Emerson should be ready for the 2027 season.
He’s expected to have limitations for most or all of his winter hitting work and could be monitored closely during Spring Training. His path remains an everyday job on the left side of the infield. His obstacle is proving that the hitter Seattle saw early in his debut — not the injured guy who struggled later — is the version it can expect over a full season.
The Mariners guaranteed Emerson $95 million before his first major-league game because they believe he can become a franchise guy. In 2027, we need to see the first sustained evidence that they were right.
Three Mariners Prospect Sleepers Who Could Arrive Ahead of Schedule
Felnin Celesten, SS
Celesten is the more realistic of our two sleepers, although even his current MLB Pipeline timeline points to 2028. The switch-hitting shortstop won Northwest League MVP honors after batting .314 with a .943 OPS for Everett, then earned a promotion to Double-A. His defense gives him a path that doesn’t depend entirely on overpowering minor-league pitching.
The opening is more obvious than some would initially think. Celesten is a true shortstop who can change how Seattle arranges Emerson, Arroyo and the rest of its infield. His obstacle is experience. He still needs to prove his offensive breakout will travel against upper-level pitching.
A strong first half at Double-A could make him a late-season possibility.
Boston Smith, C
Smith is the sleeper with the cleanest path to making an impact without winning an everyday job. The left-handed-hitting catcher erupted during his first full professional season, batting .274 with 31 home runs and a .990 OPS across four teams. The Mariners acquired him from the White Sox in the Luis Castillo trade, and he immediately announced himself by homering five times in his first six games with Double-A Arkansas.
The opportunity is sitting behind Cal Raleigh. The Mariners could need a backup catcher capable of providing more than occasional rest, and Smith’s power could give the lineup a legitimate threat on days Raleigh serves as the DH.
There are a couple obstacles here. Johnny Pereda (.300/.366/.389 with 2 home runs, 8 RBI in 90 at-bats) was probably the best backup catcher the Mariners have had in recent memory. He also remains under club control and is still pre-arbitration eligible. Smith must prove his receiving, game-calling and throwing are ready for major-league pitching. He also struck out in nearly 30 percent of his plate appearances, a weakness advanced pitchers will attack relentlessly.
More defensive flexibility could help him avoid being blocked. The White Sox gave Smith time in left field, and he appeared at several positions, including third base and left field, during college. Seattle has focused on developing him behind the plate, but the organization believes he remains capable of moving back to the outfield if needed.
That flexibility will be huge because Raleigh isn’t going anywhere. Smith doesn’t need to become Seattle’s catcher of the future. He needs to show enough defensive reliability, left-handed power and positional value to become part of the present.
Ace Reese, 3B
This is the fun long shot. Though some could argue for Jonny Farmelo. Seattle selected the Mississippi State third baseman with the 24th pick in the 2026 draft, and he demolished Class A pitching during his brief professional debut. Reese hit .440 with a .530 on-base percentage over 100 plate appearances.
100 plate appearances in Class A doesn’t mean Reese is destined for a rapid climb to Seattle. Reese’s current Pipeline ETA is 2029, and he has multiple levels to clear before the Mariners should consider him a major-league option.
But college hitters can move quickly, third base remains an unsettled position and Reese’s combination of contact, patience and left-handed power gives him a chance to wreck conservative timelines. We’re not saying he’s on some Jac Caglianone-esque rise, but it’s fun to think about.
For Reese to actually reach Seattle in 2027, everything would have to move fast. He would need to receive a spring training invite, flash some pop, handle High-A immediately, reach Double-A without losing his offensive identity, and leave the Mariners convinced that their best third-base solution is already inside the organization.
That’s a lot, and it’s why he’s a sleeper rather than one of the four primary prospects. It’s also why we should keep watching.
This reflects Seattle’s roster and prospect information as of Oct. 15, 2026. We’ll revisit the list before Spring Training after the Mariners complete their major offseason roster moves.
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