M’s Draft Profile: RHP Seth Hernandez would be swinging for fences

On Seattle Sports’ Brock and Salk this week, they’ve been letting producer Lyle Goldstein take the reins for a daily Seattle Mariners draft profile segment.

M’s Draft Profiles: SS Arquette | LHP Arnold | SS Holliday

Goldstein is also half of the Marine Layer podcast that covers the Mariners closely, and he’s had his eye on this MLB Draft for a while, especially since the M’s were lucky in the draft lottery and landed the No. 3 overall pick.

The draft starts with the first round at 3 p.m. Sunday on ESPN and MLB Network. Here’s Goldstein’s fourth profile breaking down high school right-handed pitcher Seth Hernandez from Corona, Calif.

Seattle Mariners Draft Candidate: Seth Hernandez

The pros

• Hernandez has some of the best upside in this entire draft, with his ceiling being something to absolutely dream on.

• He’s regarded as a very good athlete with room to add to an already projectable 6-foot-4, 195-pound frame.

• Hernandez throws four pitches (fastball, changeup, curveball and slider), and all of them grade as potential plus offerings.

On Thursday, Seth Hernandez threw a CG with 11 strikeouts at the #NHSI25.

Here's where he could go in the first round of the @MLBDraft this July: https://t.co/pD9Y6YRQVc

(📹: @USABaseball)pic.twitter.com/G7GrRJHQ7a

— MLB Pipeline (@MLBPipeline) April 11, 2025

• His fastball-changeup combo is lethal. He has already hit 100 mph as a high school arm and usually sits in the mid-90s with his heater, but can get up to sitting from 96-98. He is projected to sit much more in the upper 90s as time goes on.

• The changeup is one of the best pitches in the country and in this draft. The pitch has true sink and velocity-wise drops off a lot from the fastball.

• His curveball is a true 12-6 with real bite to it, and the spin rate gets all the way up towards 3,000 RPMs.

• His mechanics are extremely clean and fluid, with the delivery proving to be repeatable

• He’s slightly on the older side for a high school pitcher, as he will be 19 years old on draft day.

The cons

• Though he already throws a ton of strikes and fills up the zone, his actual command – specifically with his off-speed pitches – will need to improve a bit over time.

• Hernandez has the lowest floor of all of the top prospects in this draft, simply because the track record on prep arms (especially right-handed prep arms) towards the top of the draft is not an incredibly lucrative one. Often that has to do with the innings limit not being built up, the maturation as a pitcher lacking compared to college pitchers, and the injury risk being a bit higher.

• The Mariners seldomly select high school pitchers with high draft picks, having drafted four college pitchers in the last seven years.

The verdict

Ultimately, the Mariners almost never get the opportunity to pick this high in the draft, and they essentially lucked into having this No. 3 pick thanks to the lottery. Therefore, this feels like a chance to try and swing for the fences on the chance to get a star. Hernandez would be the pinnacle of swinging for the fences in this draft, as he has true ace potential if everything truly clicks. Personally, I would be absolutely fired up to see the Mariners select Seth Hernandez.

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