Seattle Mariners Top Prospects - Midseason

A complete scouting breakdown of the top prospects in the Seattle Mariners farm system, including Kade Anderson, Ryan Sloan, and more.

Author

Rhys White
August 13, 2026

Welcome to our team prospect rankings. The MLB Draft has come and gone, and farm systems are reloaded. It is time for a true refresh on all teams’ top prospects. For the rest of July, you will be getting updated Team-by-Team top prospects for every team. New reports for players that have made moves, updated reports on all players, and reports on every top prospect drafted!

These reports are generated from live looks, film study, and advanced data analysis to bring you in-depth fantasy scouting reports on every player you need to know, with today’s being the Seattle Mariners’ Top Prospects for 2026.

To get the full report, you need to be a paid subscriber. Why? These reports take a ton of time, and I feel like they are as good as any in the industry. It is filled with advanced data, scouting thoughts, live look reports, long-term outlooks, and more. Each team report is around 8,000 words to help you better understand the prospects. I include peak projections, future fantasy grades, variance factors, and dynasty buys and sells. To see a preview, check out the article below. If you are a Dugout member, scroll down for the Mariners top prospects.

Seattle Mariners Top Prospects for Dynasty

2026 Graduates: Colt Emerson

Format: Name, Position, 2026 OD Age, Height/Weight, Highest Level

Seattle Mariners Top Prospects for 2026

1. Ryan Sloan, RHP, 20, 6’5”/220, AA (Prev Rank: 4)

2026 Update

Ryan Sloan has some pretty outlier pitch and release traits, and of anyone in this system, he has the highest upside, while also having a solid floor for a pitching prospect. He has a 5’6” release height, and gets 6’10” of extension down the mound. His fastball averages about 96 mph and gets about 16 inches of induced vertical break with 6 inches of horizontal break. He complements that with a sinker that gets 9 inches of IVB and 12 inches of horizontal break. The headliner of the repertoire is a double-plus sweeper that sits in the mid-80s and gets 13 inches of sweep. There is a solid changeup here as well to go along with a cutter. There is a pretty unique feel for spin here, and it would not shock me if he and the Mariners were able to add a few more pitches to the repertoire. The upside here is well… I don’t want to say ace, but outside of Seth Hernandez, no other pitching prospect has this much upside.

Sloan is definitely one of my pitching prospect crushes and has been since the draft. After being selected 55th overall in the 2024 draft, Sloan hit the ground running in his first pro season, pitching 82 innings between Single-A and High-A, posting a 3.73 ERA. His FIP of 3.18 and xFIP of 3.21 were both strong, and he walked just 4.5 percent of hitters.

The fastball sits in the mid-90s, touching 98. Throwing from a lower 5’5” release height, Sloan creates decent IVB, between 13-15 inches, while showing eight to ten inches of arm-side run. He lands the fastball in the zone and locates it well.

Dialing it back, Sloan has an impressive splitter that sits in the 88-90 mph range. It has negative one inches of IVB and 11-14 inches of glove-side movement. It plays exceptionally well off his fastball as the depth on the pitch has improved. It looks plus or better.

The sweeper achieves good horizontal separation in the other direction, averaging 16 inches of sweep and occasionally reaching nearly 18 inches. It sits in 82-84 mph range with high spin rates.

If Sloan becomes one of the top pitching prospects in baseball in 2026, I would not be surprised.

FFG: SP2

90th Percentile Peak Outcome: 170 IP/3.30 ERA/200 K

Variance: Very High

Buy/Sell: Buy!

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