A Full Breakdown of the Seattle Mariners prospects headed to the Arizona Fall League

The Arizona Fall League rosters have been released this week with a lot of intriguing prospects on each team. There are six teams full of prospects from Major League teams that will play starting October 6th. I’ll be writing an article and making Twitter posts about each team’s roster. This will cover the prospects from the San Diego Padres A Full Breakdown of the Seattle Mariners prospects headed to the Arizona Fall Leaguewho will be on the Peoria Javelinas this fall. The team will consist of players from the Baltimore Orioles, Seattle Mariners, Cincinnati Reds, and Minnesota Twins as well.

San Diego Padres:

Isaiah Lowe RHP: After a shoulder injury ended his first professional season in 2023 the former 11th round pick had a great second season especially in Low-A where he pitched to a 3.00 ERA through 72 innings and made the All Star team but his numbers at the end of the season once promoted to were worse. In 7 starts in High-A to end the season Lowe pitched to a 3.05 ERA and cut his strikeout rate from 29.7% in Low-A to 14.9% while upping his walk rate by 2%. This season he pitched entirely in High-A making 22 starts and pitching in 91.2 innings. He again struggled pitching to a 5.69 ERA. He was still struggling with whiffs only striking out 16.2% of batters and his walk rate jumped to the highest of his career at 11.8%. Lowe tends to get a lot of flyballs and has struggled with homers in High-A as well. Lowe’s fastball sits in the mid to low 90s but can touch 97 mph at times. He was known for his slider that sits in the low 80s and had a 44% whiff rate in 2024 but hasn’t been working in High-A. He also has a changeup that he can command all around the zone. In the past Lowe has shown good control and a solid enough pitch mix to get hitters out but the struggle in High-A could keep him stuck there another season especially if he continues to perform poorly this fall. 

Maikel Miralles RHP: After his first state side season mostly working out of the bullpen Miralles transitioned into a starter mostly this season starting in Low-A before an injury sidelined him for about a month and a half. After coming back Miralles continued to struggle, throwing a combined 55.2 innings before and after the injury to a 5.17 ERA. He’s never been a strikeout pitcher only striking out hitters 20% of the time but he struggled with walks in Low-A walking 13.3%. That came from a struggle to throw strikes with only a 26.2 CSW%. Even with the struggling numbers he was eventually promoted to High-A where he started 2 games throwing 12.2 innings and really improved. He gave up 3 runs in his first start and none in his second while only walking 1 batter total. The Padres wanted to see more and promoted the 20 year old to AAA where he made one outing in the 9th inning of the September 14th game throwing 0.2 inning giving up 4 runs. Looking at his Statcast data from that game Miralles obviously doesn’t have overpowering stuff with a fastball that sits around 93 mph that only averaged 12.9 inches of induced vertical break. He throws a cutter or harder slider that sits 88 mph with not much movement and a changeup at the same speed with some fade but not much. 

Carson Montgomery RHP: Drafted in the 11th round of the 2023 draft after some struggling seasons at Florida State, Montgomery looked good in his professional debut season where he pitched in 7 innings to a 3.86 ERA before being shut down with Tommy John. Because of the surgery Montgomery hasn’t pitched in a pro game all season only getting some outings in back field games getting ready for the fall. Even with the struggles at FSU Montgomery showed off some nasty stuff in college. His fastball has a lot of energy hitting the high 90s often with some natural sink on it. He pairs that with a great slider with a ton of horizontal movement that gets a ton of whiffs. His problem throughout college was and in the few innings he threw in 2024 was an inability to throw strikes. In those 7 innings only 12% of his pitches were called strikes and he walked 20% of the batters he faced. This problem has stayed with Montgomery throughout college and when playing on summer ball teams. Still I’m excited to see what he looks like after Tommy John this fall. 

Johan Moreno RHP: The 2023 international signing out of Venezuela has struggled since coming to the states. In his first full season in the US in 2024 he pitched 51.2 innings between the Complex League and Low-A to a 5.40 ERA. He struggled to get strikeouts with only a 18% rate while walking 14% of batters. This season he was a multiple inning guy out of the bullpen starting in Low-A again and throwing 68.1 innings. He improved with a 4.48 ERA in Low-A. He was able to get a lot more strikeouts at a 27.1% rate while keeping his walks down a bit to 11.1%. He also gave up less home runs in more innings. This earned him a promotion to High-A where he only pitched 7 innings before the TinCaps season ended and was promoted to AA to get 3.2 more innings. At both stops he struggled against more experienced hitters even with mostly throwing an inning out of the bullpen. With no public data I can’t confirm it but he’s said to have a mid 90s fastball and tight slider that has some life. It’ll be fun to get some data on him this fall. 

Tucker Musgrove RHP: A very weird career so far for Musgrove. He was drafted in the 7th round of the 2023 draft out of NAIA school the University of Mobile. Originally Musgrove was going to be a two-way player like he did at Mobile hitting .397/.485/.635 in his Junior year while serving as the team’s closer throwing 18 innings for a 3.00 ERA while striking out 23. While being medically tested by MLB teams it was found he had a torn UCL and had to have Tommy John surgery. Musgrove missed the end of the 2023 season and all of 2024. After rehabbing the Padres moved him to a full time pitcher and after two years he finally made his professional debut in Low-A Lake Elsinore at the end of April. The Padres have been very careful with him especially after he was on the injured list twice this season. He only pitched in 20 innings in 2025 to a 5.40 ERA but struck out 30.6% of batters. His fastball has been the main story clocking in around 96 mph and can hit 100 mph while averaging 17” of induced vertical break and around 2500 RPM. He throws a sweeper to pair with it that sits in the mid 80s and has 14” of sweep and around 2900 RPM. He mixes in a sinker, regular slider, and curveball at times too. He has absolutely nasty stuff and the pitch mix to be built up as a starter. He walked 11.8% of batters this year but kept his walks down for the most part in college. A really exciting arm in the Padres system that I’ll be watching closely this fall. 

Ethan Salas C: After breaking onto the scene in 2023 after playing in a Spring Training game at 16 years old Salas followed that up with a solid 48 games in Low-A hitting .267/.350/.487 for a 123 wRC+ but struggled at both High-A and AA that season after being promoted late. He started the 2024 season as one of the highest ranked prospects in baseball but really badly struggled at High-A slashing .206/.288/.311 for a 75 wRC+ in 111 games. Even with that he continued to climb and in his 19 year old season in 2025 started on the AA roster. He was only able to play in 10 games before he suffered a lower back stress reaction. In those 10 games he again struggled slashing .188/.325/.219 for a 75 wRC+. Even though he’s been cleared to play for the past month the Padres have held Salas back to working out at the Arizona complex to get him ready for his fall league appearance. He played in the fall league last season as well hitting .228/.327/.424 with 4 homers. I’ll say I’m lower on Salas than most. He has a very weird swing that tends to get under a lot of fastballs and he doesn’t make a lot of contact as some hoped. I can see the upside with his power though as he can grow more into his frame with more muscles and show the potential for big raw power but he hasn’t shown it often enough in my opinion to be as highly rated as he is. His defense is very good though he has an above average arm and great pop time to throw out runners. He is already a solid framer and could become one of the best in baseball with more time. His blocking though was really bad in 2024 but seemed to improve in his limited games in 2025. Most publications have Salas making his debut towards the end of next season but I still see him as a project whose swing needs to be molded a bit more. It’ll be interesting to see what adjustments he’s done with coaches while rehabbing. 

Ryan Jackson INF: The 17th round pick out of USC just last season has already climbed up to AA this season. After a few games in Low-A last season after the draft Jackson started there this season playing in 62 games hitting .298/.442/.418 for a 147 wRC+. He walked more than striking out as well at 19.2% of the time. He was rightfully promoted to High-A where he was worse hitting .234/.357/.287 for a 85 wRC+ in 48 games. He was still walking a lot and his strikeout rate actually dropped from Low-A but even with a high contact percentage his hits weren’t finding the grass and his BABIP dropped from .368 in Low-A to .279 in High-A. He was promoted to AA for 19 games at the end of the season and really struggled there hitting .194/.270/.224 for a 52 wRC+. In the small sample size he only made contact on 70.5% of pitches and his strikeout rate jumped to 24.3%. Jackson’s never going to be a power hitter standing at 5’10” 180 lbs but has shown a great knowledge of the zone and decent contact ability. He’s jumped all over the infield defensively playing games at second, third, and shortstop as well as 8 games in left field. It seems like the Padres are turning Jackson into a contact bat who can play anywhere. 

Braedon Karpathios OF: After playing only one season at Junior College Harford Community College Karpathios was draft eligible and went undrafted in the 2022 draft. He was picked up by the Padres and has slowly climbed the ranks, eventually landing in AA for the last month of the season this year. This season in High-A he hit .254/.370/.410 for a 125 wRC+. He has a great knowledge of the zone rarely ever chasing especially at breaking balls but struggles with contact especially in the zone. This season between High-A and AA he only has a 72.9% contact rate and whiffs almost 40% of the time. With that advanced knowledge of the zone he walked 14% of the time this year but struck out 28%. He has some power in his bat too hitting 15 homers this year and 40 extra base hits. After being promoted to AA he struggled a bit in 21 games. He hit .225/.295/.425 for a 107 wRC+ still good but he was walking less and striking out more. His bat has potential if he can get the whiff rates down. His defense is solid at all outfield positions. He doesn’t have the speed to play center at the next level but after being a pitcher at his JUCO he has a big arm and can easily be a solid right fielder. I’m excited to see what he can do against the talented players in the AFL this year.

Thank you for reading for shorter breakdowns check out my Twitter @drew-durstock. Each day I'll release a new team's prospect breakdown.