Seattle Mariners 2023 Top Prospects List: 30-21 (2024)

Today we crack into the Top-30 for our list of the Seattle Mariners top prospects at the outset of 2023! This group features a delightful medley of prospect types, from former top picks to fringy depth players, notable international signees and minor league veterans. Each has their feats and warts. To catch up on the first installment (Nos. 45-31) as well as our grading rubric, click here.

...continuing from Tier 5

30. Milkar Perez, 1B/3B

Age: 18 / B/T: R/R / Signed: 2022 / Final level in 2022: DSL / MLB ETA: 2028
2022 stat of note: 20.6 BB% (!!!)

There might not be a prospect that C’s the Z more than Milkar Perez in the entire Seattle system. The 21 year old Nicaraguan is doing his best to walk every single time he comes to the plate, running gaudy base on balls totals at every step of the minor leagues. Perez struggled mightily in his first stint of A-ball last season, demonstrating the limitations of a purely OBP-based path to success, with a walk rate over 20% yet not having hit a home run stateside. He also received some high-leverage work this spring as one of the starting nine consistently for Team Nicaragua in the World Baseball Classic. The key to Perez’s ceiling is the power development. With an advanced eye and approach beyond his years, even average power would be a boon for Perez’s development, as he lacks the foot speed to capitalize on a pure walks and slap-hitting repertoire. Until the power is able to catch up to the rest of the hit profile, as his swing is thoroughly geared towards contact still, Perez will need to prioritize sticking at third base to help maximize his prospect profile. A move to first would be especially onerous, and Perez’s strong arm is an asset.

FV: 40 - If Perez can add pop to his bat, he would easily be one of the more intriguing bats in the entire system. Unfortunately, we are talking about a whole lot of pop that needs to be added with few results to back up the possibility. It’s not impossible to do and his hot start is promising, but not enough to write home about. -ME

29. Juan Then, RHP

B/T: R/R / Age: 23 / Traded for: 2019 / Final level in 2022: AA / MLB ETA: 2024
2022 stat of note: 12 IP

The Mariners continue to show faith in Then, despite a bumpy few years since his reacquisition from the Yankees in exchange for Edwin Encarnacion. Then has been lurking on the Seattle 40-man since 2020 and has unfortunately battled injuries that have curtailed both his 2021 and 2022 seasons. With middling results thus far, the 23 year old is likely entering a “prove it” season, where mixed results could amount to him being a DFA casualty, even after surviving the yearly roster churn for several seasons. Then should be given ample opportunity to pitch in a bullpen role, and mid-90’s velocity coupled with a nasty changeup should serve him well as a backend reliever. There are several relievers on the edge of big league readiness, but as we’ve seen Seattle go to Tacoma’s veterans who are off the 40-man first before pulling from younger arms like Then, the club still wants to see consistency from the fireballing Dominican.

FV: 40 - Then will need to make the big leagues as a reliever, but the above average velocity puts him ahead of the game. Command, consistent health, and continued development of his offspeed pitches will determine whether Then is able to finally crack the code and make it to Seattle. -ME

28. Sam Carlson, RHP

B/T: L/R / Age: 25 / Draft: 2021 (9th) / Final level in 2022: A+ / MLB ETA: 2024
2022 stat of note: 13.4% BB to 15.3% K

Sam Carlson, the Mariner’s second round pick following Evan White in the 2017 draft, has had some incredibly bad luck beginning his big league career. The Tik-Tok’n Tommy John warrior has been absolutely decimated by injuries throughout his career. That said, Carlson has adapted every step of the way and shown admirable tenacity in overcoming a myriad of injuries many others could not. The former second-round pick is now working as a sidearming reliever. His fastball velocity has ticked up slightly from the low-90s it sat in his rotation time, and the slider sweeps across the zone a la Penn Murfee.

If the velocity bump is sustainable, Sam could find a fast track up the system as a reliever. As his command has been intermittent as well, Carlson needs to show he can miss bats repeatedly in shorter outings. Health is the primary focus for Carlson at this point in his career, who needs to string together some effective innings over the course of a full season to fully realize his current prospect pedigree.

FV: 40 - The complete rebranding of the arm angle and delivery is a great tribute to his adaptability, however until we can observe a marked uptick in the stuff, it’s an uphill battle for Carlson to reach the bigs. Please baseball gods, let Sam stay healthy. -ME

27. Ashton Izzi, RHP

B/T: R/R / Age: 19 / Draft: 2022 (4th) / Final level in 2022: HS / MLB ETA: 2027
2022 stat of note: Izzi & his HS rotation-mate Noah Davis (CHW) both received 7-figure signing bonuses in the 2022 draft

Ashton Izzi, similar to his 2022 draft companion Walter Ford, is a high-ceiling prep hurler. Yet to play in affiliated ball just yet, the lanky right-hander has shown excellent promise with a fastball that already sits in the low-to-mid 90’s and a tight slider that has been in mid 80’s. Also touting an excellent split-changeup, Izzi has shown an advanced arsenal that only needs to be molded by the technicians over at the Seattle Mariner Pitching Lab LLC. I am personally much higher on Izzi than most outlets and can easily see him taking a huge step forward with increased physicality and polish. The Mariners drafted the Illinois youth as a long-term development project, however it would not shock me if we saw Izzi for a brief stint in the Cal League at some point in 2023.

FV: 45 - Izzi is a high variance prospect that is very hard to pin down precisely what we have without any knowledge of his development. That said, the potential is one to dream on and could develop into a legitimate rotation starter. -ME

26. Travis Kuhn, RHP

B/T: R/R / Age: 25 / Draft: 2019 (19th) / Final level in 2022: AA / MLB ETA: 2024
2022 stat of note: Appeared in a team-leading 50 games for Arkansas

This part of the M’s system is flush with atypical routes to prospectdom, including Kuhn and his late start on baseball. The San Diego area kid performed well as a bullpen arm for the Toreros of the University of San Diego, earning a 19th round selection from Seattle. When a reliever’s delivery comes to mind, Kuhn’s fits the bill, with significant effort uncorking into a powerful fastball-slider combo. The heater runs significantly in on righties with impressive sink to boot, pumping to the mid-to-upper 90s while the tight, sharp slider works in the mid-to-upper 80s. Though his repertoire is theoretically well-suited to being a groundball specialist, Kuhn does issue free passes with more consistency than might be hoped. Additionally, he’s been working up in the zone more frequently, helping him miss bats but making his ability to elude barrels all the more vital, as his walks have thus far evaded being cashed in at pace.

FV: 40 - Kuhn’s stuff and work ethic has drawn acclaim from inside and outside the organization. His command, to date, has not. This is a steadier bullpen profile, but it’s still a middle relief trajectory in all likelihoods. -JT

25. Spencer Packard, OF/1B

B/T: L/R / Age: 25 / Draft: 2021 (9th) / Final level in 2022: A+ / MLB ETA: 2024
2022 stat of note: 13.4% BB to 15.3% K

The former Campbell Camel can really slug it, bashing 12 HR in 307 PAs last year. There’s that famed “different sound” when his bat impacts the ball, and his elite eye at the plate helps him find the right pitches to impact. But Packard doesn’t sell out for over-the-fence-power, instead taking what the pitcher gives him and spraying it all over the field with damage. His swing is compact, and while he has a muscular, stocky frame, his power comes from his strength more than bat speed. As an older prospect with a limited defensive profile and less speed than a golf cart, he’ll need to continue hitting like this in order to keep climbing the ranks, but so far, so good.

FV: 45 Packard’s prodigious power and propensity to ptooie on poor pitches provides a plus possibility he pops, but it’s a perilous path forward. -KP

24. Juan Mercedes, RHP

Age: 23 / B/T: R/R / Signed: 2016 / Final level in 2022: A+ / MLB ETA: 2025
2022 stat of note: 4.16 K/BB ratio

Mercedes, entering his seventh year as a Mariner farmhand in 2023, is an intriguing arm that shows some promise at the lower levels of the minors. Showing a strong ability to limit walks and rack up strikeouts, the next step for the Dominican native is to show tangible improvements in run prevention. Already 23 years old and repeating High-A Everett, it is a make or break year for the young pitcher. With a dynamite sweeper as his primary weapon, a move to the ‘pen may aid his chances at seeing big league time with the hope the stuff would tick up a notch or two. Mercedes can dilate his powerful slider to feature more vertical movement as well, to quality effect.

FV: 40 - Mercedes is likely a swingman/back of the bullpen option available to eat some innings, but already at an advanced age with limited success puts him in a difficult spot. -ME

23. Starlin Aguilar, 1B/3B

Age: 19 B/T: L/R Signed: 2021 Final level in 2022: R (ACL) MLB ETA: 2027
2022 stat of note: hit .291 in 185 PAs

Aguilar, a highly-touted international signing nicknamed “Baby Devers,” has been slow out of the gates in starting his professional career. He showed solid plate discipline in the DSL but that trickled away some in the ACL, and he hasn’t hit for anything resembling power in two seasons as a pro. On the bright side, he’s gotten after it in the gym and has trimmed down and muscled up since signing, and he’s still just 19 years old, so maybe with great contact will come greater power yet.

FV: 45 - Defensively Aguilar will have to be able to hang at third base or a corner to make up for his bat, and that’s no guarantee. 2023 will give a good indication as to whether or not the Mariners have Baby Devers or Baby Smoak on their hands. -KP

22. Juan Pinto, LHP

Age: 18 / B/T: L/L / Signed: 2021 / Final level in 2022: DSL / MLB ETA: 2027
2022 stat of note: 8.6 BB/9

Pinto is a long levered lefty that was signed out of Venezuela in the 2021 international free agent class. Pinto is all projection right now, particularly after an erratic, whiffs and walks journey through the DSL last year. With fluid mechanics from the left side, a beautiful 12-6 looping curveball and a fastball that sits in the low 90’s, any additional physicality is only going to help the stuff play. He needs to learn to control the baseball and continue to add strength to his lanky frame, but as an 18 year old already with experience at the DSL level, he has plenty of time to continue improving. Pinto’s smooth athleticism down the mound lends well to him starting at the next level, but he will need to develop a viable third pitch on top of quelling the aforementioned control problems in order to begin thinking of affiliated ball.

FV: 45 - Pinto is probably closer to a 40 FV for me but I have to respect the upside of an 18 year old lefty already pumping velo in the low 90’s. Pinto is far from a sure thing, but his proponents aren’t delusional in seeing the potential of a mid-rotation arm. Variance is exceptionally high. You’ll also note Pinto is the highest-ranked LHP in the system. -ME

21. Robert Pérez Jr., 1B/OF

Age: 22 / B/T: R/R / Signed: 2016 / Final level in 2022: A+/AFL / MLB ETA: 2024
2022 stat of note: 27 HR across two different levels (A/A+)

Bobby Bombs has some serious thump in his bat. Swatting 53 extra base hits that included 27 homers across two different levels, Pérez Jr. saw a large uptick in nearly every offensive category in 2022. Once a true first-base only prospect, Pérez Jr. has been given some leash to stick in corner outfield at his new home in Double-Arkansas. Should the switch be a permanent one and Pérez Jr. is able to stick in the outfield while maintaining his undeniable offensive prowess, the young Venezuelan could become a force to be reckoned with and one of the more intriguing prospects in the entire system. The next frontier of development will likely include a heavy dose of C’ing the proverbial Z in order to cut down on a K rate that is high, but not overly problematic for someone with his power. In a system vanishingly short on young hitting prospects in the high minors, he shoulders a larger burden of proof than may be fair to expect.

FV: 45 - I’m ultimately not sold on whether or not he sticks in the outfield, but in all honesty, that’s not what matters with Pérez Jr. It’s all about the bat. Always has been. Always will be. The AFL Home Run Derby champ will need to slug his way to the big leagues, and will have ample opportunity to do so. He’s being heavily challenged with an assignment up to Double-A Arkansas as a 22-year-old, as Bobby Bombs is the only hitter under the age of 24 at Double-A or higher in Seattle’s system besides Julio Rodríguez and Jarred Kelenic. -ME