Sam Carlson, Seattle Mariners
Reading Time: 8 minutes

POSTED: Nos. 31-40
POSTED: Nos. 21-30

Monday: Nos. 6-10
Wednesday: No. 5
Thursday: No. 4
Friday: No. 3
Saturday, Feb. 27: No. 2
Sunday, Feb. 28: No. 1
Monday, March 1: Best Tools
Tuesday, March 2: How many Mariners prospects would be No. 1 elsewhere?
Wednesday March 3: Projected 2024 Lineup, Rotation, Bullpen
Thursday, March 4: Projecting the Top 10 Prospects after the season

The Seattle Mariners farm system is as deep as it’s ever been. There’s big-league talent beyond the club’s Top 20. Below is prospects Nos. 11-20.

Important note: There’s not a significant difference between 20 and 13, at least not as much as seven entire spots in a good farm system would suggest, but here’s a delicate balance between upside, risk, and ETA.

11 Juan Then RHP 2022 FASTBALL A+/AA
12 Zach DeLoach CF 2023 HIT A/A+
13 Jonatan Clase CF 2025 RUN A/A+
14 Austin Shenton 3B 2022 HIT AA
15 Sam Carslon RHP 2024 FASTBALL R/A
16 Andres Munoz RHR 2021 FASTBALL AAA/MLB
17 Connor Phillips RHP 2023 FASTBALL R/A
18 Levi Stoudt RHP 2023 FASTBALL A/A+
19 Jake Fraley OF 2021 HIT AAA/MLB
20 Milkar Perez 3B 2024 HIT R/A

20. Milkar Perez, 3B
Perez is still raw and because he lacks athleticism is limited defensively. The Mariners believe his arm strength and hands allow him to work at third base, but there are questions as to whether or not his power will.

He’s a switch hitter but is better from the left side and the difference may be stark enough to eventually abandon the efforts from the right side. For now, he shows above-average raw power as a lefty.

Perez’s calling card is bat-to-ball skills that generate hard line drives thanks to good bat speed. But the power is critical here, as he’s not athletic enough to project to the outfield, though his arm would play, and a move across the diamond to first does nothing but add pressure to the bat.

He’ll have to hit regardless, and if the power doesn’t come he’ll have to hit an awful lot to profile as a regular. The Mariners like a loot of the intangible, however, and a .280/.350/.450, doubles-driven bat isn’t that far from what Kyle Seager brought to the table in his prime, so… no sneezing.


55 50+ 45 60 45

19. Jake Fraley, OF
Like Bishop, Fraley is starting to run out of time to show he’s an answer to a question Seattle is asking.

What we know is Fraley can run some and cover ground in the outfield. He displayed improved power in 2018 and 2019 after adding some bulk to his frame, but his game plan in his short stints in the majors was exposed and he wasn’t given a lot of time to make adjustments.

The swing is short enough and the bat speed is above-average, but he’s had problems staying back on soft stuff and since he may not profile in center he’s unlikely to serve as anything more than a part-time option if he doesn’t piece together a hit + doubles package at the plate.

He’ll be 26 in May and has a shot to break camp with the big club. His shot to show he’s more than an extra may be limited to a few weeks of at-bats, or come with another team.


50 45+ 50+ 45 55

18. Levi Stoudt, RHP
After Tommy John surgery two summers ago, Stoudt’s arm strength is all the way back as he touched 97 this past fall. He came to pro ball with an above-average split-grip changeup projecting to be plus or better in time.

He’s going with the slider as his breaking ball of choice, but has a curveball in his pocket if he ever wants to go back to it; it was below-average at Lehigh, but flashed depth.

I’m not as high on Stoudt at this stage as most others because he’s yet to throw a professional pitch and lacks physical projection at 6-foot-1 and 200 pounds — not to mention has the zipper on his resume now, and is already 23.

I think there’s a very good chance he’s a reliever, but has a shot to be a good No. 4 or a light if things break right, and the fact he projects for average command lends confidence to the median projection. He’s at least two and a half years away in a rotation role, but if he’s transitioned could move rapidly to the majors as a legit three-pitch arm capable of pitching in high-leverage situations.


55 (93-97) 50+ (82-86) 45+ (77-81) 60 (85-88) 50+

17. Connor Phillips, RHP
Phillips is certainly more of a project than is Stoudt, but there’s a lot more projection in the frame (6-2/190) and despite technically being a college draftee (McLennan JC, TX) he won’t turn 20 until May.

He’s tagged 98 mph with his fastball and his cruising velocity is an easy 92-95 with some run. He added curveball last summer, but his hard slider has flashed plus and on occasion last spring showed an average change.

He’s further away from his ceiling, but there’s probably another step for Phillips that isn’t there for Stoudt, and both come with there own risks. For Phillips, it’s inconsistent control and command, and a delivery that’s come apart with runners on base.


65 (93-98) 55+ 45+ NEW 45+

16. Andres Muñoz, RHR
Muñoz is an easy scouting report. Prior to the injury he was 97-102 mph with an average slider that plays up because the velocity is essentially burning cheese.

Muñoz is not afraid to throw in on right-handed batters, and his heat shows effective run to his arm side and tons of life at the top of the zone.

The control problems stem mainly from his high-effort delivery yanking him hard to the first-base side of the mound at release point. If he can stay in-line more everything, including (as ridiculous as it sounds) the triple-digit heat. But there are also some arm path adjustments that could me made to help him with consistency.

How much the Mariners want to mess with that with the righty coming off March, 2020 Tommy John surgery remains unclear, but a healthy Muñoz sees the majors this season and when he does it’s must-see TV, even though it would surprise no one if he wasn’t living in the upper-90s right out of the gate.

One reason the Mariners might be aggressive in trying to clean up Muñoz’s mechanics is his history of arm issues, almost exclusively with the elbow.

Seattle is hoping he can be their relief ace moving forward, and the stuff suggests that’s plausible. There’s just a ways to go for it to occur so I have a hard time ranking him higher than this.


80 (97-102) 60 (84-87) 40 N/A N/A

15. Sam Carlson, RHP
I’m high-man on the now 22-year-old Carlson despite the fact he’s coming off 2019 Tommy John and has faced just 13 batters in three and a half years since the Mariners selected him in Round 2 of the 2017 Draft and handed him $2 million.


He possesses a projectable starter’s repertoire, including an advanced changeup, sinking fastball up to 96 mph, and potential for an average or better slider thrown from a true three-quarters slot. He’s also an absolute beast, both physically and in terms of mental toughness.

Carlson is one of the best athletes in the system and as built himself into a monster, adding good weight and maintaining an explosive lower half.

This is the ultimate high-risk, high-reward for many, but I see No. 3 upside with a good middle reliever’s floor, and I think he’s going to move a little faster than one might otherwise think because he’ll get a lot of value out of his sinking fastball in the lower minors.

I imagine Carlson has a chance to start in Modesto in May, but it wouldn’t be shocking if Seattle held him back a bit to easily manage his workload in what we all hope is his first full season in pro ball.


60+ (90-96) 50+ (83-86) 40+ (76-80) 55+ (83-85) 45+

14. Austin Shenton, 3B
I may also he high-man on Shenton, but I believe in the hit tool and think his power will show up more after he gets to the big leagues, not unlike Kyle Seager, who managed just 22 homers in 1245 plate appearances spanning 269 minor leagues games.

What Shenton doesn’t quite have — or at least hadn’t shown through 2019 — is Seager’s hands and feet at third base. I think he ends up fringe-average at best defensively at the hot corner, but there’s a chance the bat plays and then some, covering a move to a corner-outfield spot.

He sees the ball well and might be the smartest hitter in the system. Shenton’s strengths also fit T-Mobile Park very well; he likes to use both gaps for doubles, can go line-to-line in contact situations and his pull power plays to Mobi’s right-field naturally.

Shenton may be fit to start 2021 in Double-A Arkansas with a chance to see Tacoma by year’s end.


55 50+ 45 50 45

13. Jonatan Clase, CF
And I KNOW I’m high-man on Clase.

The 18-year-old kid starred for the DSL club two summers ago, despite most of the attention going to his more famous teammate, Noelvi Marte.

Clase swung and missed a bit too much during that stint, but has bat speed, instincts, can run for days, and has shown the organization a work ethic that makes player development staffers giddy.

He’s actually grown a few inches and put on some good weight, but I’m told remains explosive out of the box and in the field. His speed and quickness give him a solid chance to stick in center field, though he needs a lot of experience and coaching, and a throwing program has helped him project to average arm strength.

He’s years away, and is still raw at the plate, but won’t be 19 until late May, and when he’s anywhere near a field is as energetic as any player you’ve ever seen. He does nothing half-assed, and has a chance to impact the game in a lot of ways, though power isn’t likely to be one of them to a great degree.

I’ll take a player like Clase over a high-probability back-end starter or a relief arm any day of the week and twice on game day. Clase is likely starting the season in extended awaiting the rookie season to start.


50 40 60+ 50 70

12. Zach DeLoach, CF
I warned on DeLoach three weeks after the draft when a team analyst told me DeLoach was the best ’20 Draftee he saw in 10 days watching fall ball.

DeLoach has above-average raw power to his pull side, but otherwise is a better bet to use the middle of the field, make a lot of hard contact and get on base a ton.

There may be 16-18 homers in the bat, but if there isn’t the bat may be light for a corner, putting pressure on his instincts to take over in center and make up for average speed and fringe-average arm strength.

DeLoach, too, is a left-handed bat that profiles well at T-Mobile Park, and I’m a little more bullish on the power developing than some, explaining why I have him 4-10 spots higher.

I’d like to see the Mariners ship DeLoach to Everett in May to get started.


55 50+ 45 60 45

11. Juan Then, RHP
Then, properly pronounced more like ‘Tayn’ (silent ‘h’) but likely to be Americanized to ‘Ten,’ is a bit undersized at 6-feet tall but put on some good weight over the past year-plus and his velocity exploded in instructs, reportedly touching 100 mph and living 95-plus in short outings.

The lower slot he’s deployed might impact his ability to throw a legit, repeatable changeup in a starter’s role, but it’s added deception and movement to his fastball and slider.

He has a chance to start, and the ceiling lies somewhere in the middle of the rotation, but the floor may be as a high as the next Edwin Diaz. He’s a good athlete and in years past has thrown enough strikes to believe he’ll continue to do so moving forward, despite the added effort and difference in release angle.

Then should start 2021 in Everett, where play-by-play great Pat Dillon should have one of the best rosters in AquaSox history from which to create more audio memories for the rest of us.


70+ 50+ 45+ 45+ N/A

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Jason A. Churchill

Churchill founded Prospect Insider in 2006 and spent several years covering prep, college and pro sports for various newspapers, including The News Tribune and Seattle PI. Jason spent 4 1/2 years at ESPN and two years at CBS Radio. Find Jason's baseball podcast, Baseball Things, right here.