San Diego Padres Minor-League Pitchers of the Month: May 2026

[Steve Drumwright]

There might not be much in the way of immediate help in the pitching pipeline for the San Diego Padres, but a little bit further down the ladder, there are a handful of arms who could one day be playing big roles for the Friars. In May, a few took their games to another level.

Ranking Padres' Best Minor-League Pitchers In May

Honorable Mention: Carson Montgomery, RHP, High-A Fort Wayne TinCaps

May stats: 1-1, 1.86 ERA, 4 games (all starts), 19⅓ IP, 10 H, 4 R, 4 ER, 0 HR, 11 BB, 20 K, .152 opponent average

The 23-year-old right-handed starter could have easily made the top three a sweep by the TinCaps' pitching staff. Montgomery is the Thursday starter and opened the month with two five-inning starts in which he didn't allow a run and a combined five hits. That followed his last start in April of another five scoreless innings. A 16-inning scoreless streak came to an end in the first inning of his May 21 start, but he allowed just that run over five innings. His final outing of May was a little rockier, giving up three runs on just two hits in 4⅓ innings as he issued five walks. For the season, Montgomery has a 1.98 ERA with a 12.2% walk rate and 22.4% strikeout rate.

Honorable Mention: Andrew Moore, RHP, Double-A San Antonio Missions

May stats: 0-0, 2.79 ERA, 8 games (all relief), 9⅔ IP, 2 H, 5 R, 3 ER, 0 HR, 10 BB, 22 K, 0.65 opponent average

The 26-year-old right-hander was a rock in the Missions' bullpen in May. In six of his eight appearances, Moore didn't allow a run and in another, the two runs he surrendered were unearned. His only blip was three runs in one-third of an inning May 22 vs. Frisco in which he issued four of his nine walks for the month, giving him seven in back-to-back outings. He was acquired when the Padres dealt infielder-outfielder Connor Joe to the Cincinnati Reds on May 9, 2025.

No. 3: Jesus Castro, RHP, Low-A Lake Elsinore Storm

May stats: 0-1, 2.33 ERA, 4 games (all starts), 19⅓ IP, 21 H, 5 R, 5 ER, 3 BB, 27 K, .284 opponent average

The 18-year-old right-handed starter was a strikeout machine in May, fanning 27 in 19⅓ innings over four appearances with the Storm. That included a career-high nine on May 13 against Rancho Cucamonga and came after a seven-strikeout performance to open the month. He went 5⅔ innings in each of those games. He had an eight-strikeout game in 2025 in the Dominican Summer League, where he recorded 46 in 43⅓ innings.

The younger brother of Padres prospect right-hander Manuel Castro, currently on the 60-day injured list with Double-A San Antonio, Castro had back-to-back shutout starts, one of 5⅔ in that nine-strikeout showing vs. Rancho Cucamonga and then four innings against Visalia on May 20. He walked three in those two games, but didn't issue a walk in his other two starts, in which he gave up a combined five runs.

Signed as international free agent out of Mexico in January 2025, Castro's walk and strikeout rates with the Storm are just a notch worse than they were in his debut season in the DSL. In 2025, he had a walk rate of 5.9% and a strikeout rate of 27.1%. This year, those marks are 8.2% and 24.7%. He does allow a few too many hits, though; his opponent batting average for May was .284, which included giving up a season-high seven hits against Rancho Cucamonga, and that number is .281 for the season. It was .194 last year.

No. 2: Clay Edmondson, RHP, High-A Fort Wayne TinCaps

May stats: 1-1, 0.00 ERA, 9 games (all relief), 7 saves, 8 chances, 11⅓ IP, 4 H, 2 R, 0 ER, 4 BB, 20 K

The 22-year-old right-handed closer has been one of the most efficient relievers in the minors this season. Of his eight May appearances, he didn't allow a run in seven outings, with the other being two unearned runs for a 0.00 ERA. He had two four-out saves in which all four outs were recorded via strikeouts. This came after an April in which he allowed one earned run (two runs total) in eight appearances.

For the season, Edmondson's ERA sits at a dazzling 0.43 with a .120 opponent batting average and 0.76 WHIP. In addition to his 20 strikeouts over 11⅓ innings in May, he walked four. For the month, he not only had a pristine ERA, but a .094 opponent average and 0.64 WHIP. Edmondson's lone May game in which he allowed a run came May 13 vs. Cedar Rapids thanks to a leadoff grounder that was booted. He then gave up a one-out double and struck out the next batter, but a passed ball allowed him to reach and put runners on the corners. That set up a walk-off sacrifice fly. That was his only blown save in eight chances in May. He is 10-for-11 for the season in saves.

He picked up his first win of the season in Friday's 9-8 win over South Bend, going two innings for the third time this season and striking out three. A 14th-round draft choice last year out of North Carolina-Asheville, Edmondson made just seven relief appearances at Low-A Lake Elsinore in his pro debut, walking five and striking out 11 over 12⅔ innings for a 4.26 ERA.

No. 1: Kash Mayfield, LHP, High-A Fort Wayne TinCaps

May stats: 2-0, 3.79 ERA, 5 games (all starts), 19 IP, 8 R, 8 ER, 9 BB, 24 K

It says a lot about your month when you can cough up six earned runs in one-third of an inning and the numbers still look really good. Mayfield had a rough outing in a 9-8 win over South Bend, giving up those six runs one three hits and two walks while just getting one out, the first batter he faced in his start. Three of those runs came in when the next batter after he left the game smacked a grand slam, but Mayfield had thrown 32 pitches, a high number for any single inning.

That was by far Padres Mission's No. 2 prospect's worst outing of his brief pro career. He had allowed three runs in three of his first five career outings, then in his final start of 2025 and just once this year on April 24. That outing was just one of three in nine starts this year that Mayfield has allowed an earned run, so chalking this one up as an anomaly is pretty easy to do.

His previous three outings were all five shutout innings after beginning the month with two runs in 3⅔ innings. This month also included matching his career high with nine strikeouts in a game and the highest two-game total in his 28 career starts. On May 15 on the road against Cedar Rapids, he fanned nine to match his best total. He followed that up May 22 at home vs. Dayton when he punched out exactly eight for the second time this season and third time in his career.

Mayfield represents the future for Padres pitching (unless the front office decides to empty the farm system before the trade deadline) and is looking like the front-end starter they imagined when they took him in the first round in 2024.

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