At the beginning of this month, we took a look at the hottest hitting prospects for each team. Now it’s time to shine a light on the arms.

Here are the hottest pitching prospects for each organization for the month of May, as of Wednesday. Some have been lights out from the start of the season and are on their way to a special year. Others righted the ship after a rougher start with the hopes that this month will lead to more success as the 2024 season roles on.

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AMERICAN LEAGUE EAST

Blue Jays: Fernando Perez, RHP (No. 24)
The 20-year-old right-hander has moved to full-season ball for the first time with Single-A Dunedin and is handling the transition well. He’s yet to allow more than three earned runs or two walks in any of his eight starts, and he’s completed at least five frames in each of his last five. His 91-94 mph fastball, 79-82 mph slider and low-80s changeup all have called-strike-whiff rates above 30 percent, and his 6.4 percent walk rate is the lowest among qualifiers in the organization.

Orioles: Seth Johnson, RHP (No. 10)
This is the first real look the Orioles are getting at Johnson since getting him from the Rays just before he had Tommy John surgery in 2022. He did touch Double-A for one outing at the end of last year and he’s back there now. After a relatively pedestrian April, he started showing off why he was coveted in the first place, with a 2.93 ERA, .200 batting average against and better than a strikeout per inning over four starts.

Rays: Ian Seymour, LHP (No. 18)
Seymour’s early career has been marred by injuries, so it’s notable already that his 47 2/3 innings for Double-A Montgomery rank second-most in his four Minor League seasons. But the 25-year-old southpaw has been dominant of late too with a 1.06 ERA, 25 strikeouts and only one walk over his last three starts. His 0.82 WHIP on the season leads Double-A qualifiers, while his 33.9 percent K rate tops the Southern League.

Red Sox: Luis Perales, RHP (No. 9)
Signed for just $75,000 out of Venezuela in 2019, Perales is making a case that he's the Red Sox's best pitching prospect. Armed with a riding mid-90s fastball and a power slider, he has posted a 2.60 ERA with 32 strikeouts in 17 1/3 innings in High-A in May and earned a promotion to Double-A on Sunday.

Yankees: Jack Neely, RHP (No. 24)
An 11th-round steal out of Ohio State in 2021, Neely used his devastating mid-80s slider and mid-90s fastball to place fifth among Minor League relievers (minimum: 50 innings) with a 40 percent strikeout rate in 2022 and fourth with a 39 percent K rate last year. He's at 37 percent this season in Double-A, where he has compiled a 2.19 ERA, .178 opponent average and 17/3 K/BB ratio in 12 1/3 innings this month.

AMERICAN LEAGUE CENTRAL

Guardians: Andrew Walters, RHP (No. 24)
Relying heavily on a deceptive fastball that sits in mid-90s and reaches 99 mph with plenty of carry, Walters notched more saves (26) than he yielded earned runs (16) in three college seasons at Miami. A supplemental second-round pick last July, he has been just as dominant in his pro debut in Double-A, including a 1.80 ERA, .194 opponent average and 16 strikeouts in 10 innings in May.

Royals: Chandler Champlain, RHP (No. 11)
Champlain posted a 0.52 ERA with 24 strikeouts and two walks over his first three starts of May for Double-A Northwest Arkansas, earning a deserved promotion to Triple-A Omaha in the process. He tossed a quality start in his Storm Chasers debut on May 23, allowing three earned runs over six frames, while touching 96.6 mph and getting a pair of whiffs with his upper-70s curveball. The former Yankee prospect could be an option for Kansas City in the second half.

Tigers: Jaden Hamm, RHP (No. 18)
Hamm has been one of the most dominant arms in the Minors all season long with a 1.04 ERA, 0.89 WHIP, 47 strikeouts and only five walks through nine starts (34 2/3 innings) for High-A West Michigan. A cautious approach from Detroit – including limiting Hamm to only one frame due to a 32-pitch count last time out on May 23 – has kept Hamm off the Minor League qualified leaderboards, but thanks to the impressive carry on his fastball, he hasn’t slowed down from keeping zeros on the board with scoreless appearances in four of his last five starts entering Wednesday.

Twins: Zebby Matthews, RHP (No. 20)
Another intriguing later-round arm the Twins have found, Matthews is showing that his four-pitch mix works just fine in Double-A, earning a bump up to Wichita after four excellent starts with High-A Cedar Rapids. The 6-foot-5 right-hander has allowed just two earned runs over 24 2/3 IP this month (0.73 ERA), yielding only 12 hits (.141 BAA). He also allowed just one walk -- his first of the season -- while striking out 32 over four starts.

White Sox: Mason Adams, RHP (No. 19)
Adams has displayed one of the best curveballs and some of the best control in the White Sox system since turning pro as a 13th-rounder out Jacksonville in 2022. Part of a loaded all-prospect rotation at Double-A Birmingham, he has permitted three earned runs in five May starts while fashioning a 0.91 ERA, .178 opponent average and 29/6 K/BB ratio in 29 2/3 innings.

AMERICAN LEAGUE WEST

Angels: Victor Mederos, RHP (No. 15)
Though Mederos did spend some time in the big leagues last summer, he’s not been able to consistently harness his stuff to get outs and get back to Los Angeles. After posting a 6.94 ERA in Double-A over five April starts, he found a little bit of a better groove this month. It would be nice to see him miss more bats and walk fewer hitters (9 K’s in 23 1/3 IP), he has posted an impressive 1.54 ERA, .183 BAA and 0.99 WHIP in four starts.

Astros: Jake Bloss, RHP (No. 11)
After graduating in three years from Lafayette, Bloss transferred to Georgetown and became the 2023 Big East Conference pitcher of the year and the highest pick in Hoyas history (third round). He has continued to thrive with a 92-97 mph fastball with carry and a solid upper-70s curveball, getting promoted to Double-A this month and logging a 1.27 ERA, .123 opponent average and a 22/6 K/BB ratio in 21 1/3 innings.

A’s: Grant Holman, RHP (No. 30)
While most of the names on this list are starters, sometimes you have to give a reliever dominating his due. The right-hander has now made 16 appearances with Double-A Midland without allowing a run. In May, he tossed 10 1/3 scoreless innings over nine games, giving up just six hits (.176) while striking out 10. He added two saves to give him six for the year to go along with 23 K’s in 17 1/3 total IP.

Mariners: Logan Evans, RHP (No. 19)
The Mariners may have gotten more than they realized when they took Evans in Round 12 of the 2023 Draft. Jumped to Double-A to start his first full season, he leads the Texas League with his 1.39 ERA. He’s been very stingy this month, with a 0.79 ERA, .165 BAA and an impressive 27/3 K/BB ratio over 22 2/3 IP in four starts.

Rangers: Joseph Montalvo, RHP (No. 26)
A Puerto Rican high schooler who was the Rangers' last choice (20th round) in the 2021 Draft, Montalvo pairs a low-90s fastball that plays better than its velocity thanks to carry and extension with a low-80s slider with good depth. He's on a roll in High-A with a 1.74 ERA, .164 opponent average and a 29/4 K/BB ratio in 20 2/3 May innings.

NATIONAL LEAGUE EAST

Braves: Spencer Schwellenbach, RHP (No. 3)
He had Tommy John surgery right after he signed in 2021 and pitched well across two levels of A ball last year. With the elbow injury now further in his rearview, he’s starting to take off, earning a promotion to Double-A after six starts. He hasn’t given up a run in his first two starts with Mississippi -- past three overall -- leading to a 1.59 ERA, .156 BAA and 30/6 K/BB ratio over four May stars. He was also called up for his debut in The Show to make a spot start for the Braves on Wednesday.

Marlins: Noble Meyer, RHP (No. 1/MLB No. 45)
The best high school pitcher in the 2023 Draft, Meyer went 10th overall on the basis of his mid-90s fastball, mid-80s slider, athleticism and polish. The Marlins promoted him to High-A on Tuesday after he recorded a 0.45 ERA, .079 opponent average and 33 strikeouts in 20 innings in Single-A this month.

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Mets: Jonah Tong, RHP (No. 20)
The 2022 seventh-rounder opened his season with four scoreless appearances for Single-A St. Lucie, striking out 36 in 18 2/3 innings in the process, and earned an early May promotion to High-A Brooklyn. He’s come closer down to Earth at the higher level but only by a little with a 1.69 ERA and 26 K’s in 21 1/3 frames with the Cyclones. The 20-year-old’s 92-94 mph fastball has elite carry, leading to all the whiffs, and his pair of breaking pitches gives hitters more to consider.

Nationals: Andry Lara, RHP (No. 30)
Lara fell off the Washington Top 30 because he didn’t miss many bats at High-A Wilmington last season (66 strikeouts in 98 1/3 innings). That hasn’t been the case this year. He had a 2.35 ERA with 39 punchouts in 30 2/3 frames back with the Blue Rocks to begin 2024 and earned a Double-A debut on May 17. He’s been solid for Harrisburg since with a pair of quality starts in his first two appearances. Lara’s fastball has been back up to the 92-95 mph range while his mid-80s slider has been the best at getting whiffs in the Eastern League.

Phillies: Michael Mercado, RHP (No. 30)
The Phillies acquired Mercado after the 2023 season from the Rays and added him to their 40-man roster. It’s been a long road for the 2017 second-round pick, having to contend with eventual Tommy John surgery and the pandemic. Now 25, he’s knocking on the big league door from Triple-A. His 1.15 ERA is actually up from the start of the season, when he didn’t allow a run over his first six outings. Still, he’s kept hitters to a .173 average and struck out nearly a batter per inning as a full-time starter this month.

NATIONAL LEAGUE CENTRAL

Brewers: Jacob Misiorowski, RHP (No. 1/MLB No. 23)
Milwaukee’s top prospect continues to live up to the scouting report – impressive overall numbers despite control concerns. Over four starts in May for Double-A Biloxi, Misiorowski has posted a 1.59 ERA with 19 strikeouts in 17 innings while walking 15 in the same span. His upper-90s fastball and plus-plus slider continue to play because of his elite extension, but his scattershot control will only become a bigger issue the more he faces advanced batters. It’s working for now, and soon, we could see the 2022 second-rounder reach Triple-A Nashville for the first time.

Cardinals: Quinn Mathews, LHP (No. 21)
Mathews showed improved velocity this spring compared to his Stanford days, averaging 94.8 mph on his four-seamer with Single-A Palm Beach. His changeup and slider had whiff rates above 55 percent in the Florida State League, and that well-rounded arsenal helped the southpaw strike out 27 batters over his final three Palm Beach starts (18 2/3 innings). He debuted with High-A Peoria on May 18, striking out 11 over seven innings, but was touched for five earned runs over six innings six days later. His repertoire and impressive control will still have him surging up the St. Louis Top 30 in our midseason update, assuming health.

Cubs: Will Sanders, RHP (No. 27)
Projected as a first-round pick entering 2023, Sanders had an inconsistent junior season at South Carolina and dropped to the fourth round. He got knocked around this April but hasn't allowed an earned run in four of his five May starts in High-A while posting a 1.74 ERA, .145 opponent average and 19 strikeouts in 20 2/3 innings. All four of his pitches have the chance to become at least solid offerings, highlighted by his mid-80s slider and low-80s curveball.

Pirates: Braxton Ashcraft, RHP (No. 6)
The beginning of the 2024 season didn’t go well for Ashcraft, with a 6.91 ERA over four appearances. Then something clicked after his first May start (6 IP and 4 ER). He tossed 12 scoreless innings over his next two starts en route to a 2.05 ERA this month. He also had a nifty 32/5 K/BB ratio over 26 1/3 innings for a 1.06 WHIP and 10.9 K/9 rate.

Reds: Julian Aguiar, RHP (No. 17)
The Reds’ Minor League Pitcher of the Year in 2023 has picked up where he left off last year, back with Double-A Chattanooga (where he finished last season). He’s gone at least six innings in four of his five starts this month, and went five in that fifth one, compiling a 1.80 ERA over 30 innings, allowing 25 hits (.229 BAA) and walking only four for a 0.97 WHIP.

NATIONAL LEAGUE WEST

D-backs: Spencer Giesting, LHP (Not ranked in Top 30)
The 2022 11th-rounder may not be among Arizona’s Top 30 prospects now, but it’d be impossible to ignore what he’s accomplishing in his return to High-A Hillsboro. His 0.66 ERA is tops among Minor League full-season qualifiers, and he’s combined that with a 0.73 WHIP, 46 strikeouts and 10 walks in 41 innings. Giesting is currently coming off back-to-back outings with seven scoreless innings and at least nine strikeouts, and he’ll likely be challenged with a move to Double-A Amarillo before long.

Dodgers: Maddux Bruns, LHP (No. 13)
Bruns has displayed some of the best stuff among Minor League lefties since the Dodgers made him a first-round pick in 2021 out of an Alabama high school. He often struggles to harness a lively mid-90s fastball and a big-breaking curveball and slider, but he has been dealing in May with a 1.50 ERA, .171 opponent average and 21 strikeouts in 12 innings.

Giants: Joe Whitman, LHP (No. 10)
The Giants were able to snag Whitman, the best college left-hander in the 2023 Draft, with a supplemental second-round pick. The Kent State product has advanced feel for a plus slider that he sets up with a riding 91-96 mph fastball. He has shaken off a rough April to log a 2.38 ERA, .175 opponent average and an 18/7 K/BB ratio in 22 2/3 innings this month in Single-A.

Padres: Bradgley Rodriguez, RHP (No. 28)
The 20-year-old right-hander has caught a lot of Padres fans’ attention because of his fastball that can touch triple-digits, and that offering helped him earn a move from Single-A Lake Elsinore to High-A Fort Wayne after only four relief appearances. His Midwest League time got off to a rough start with five earned runs in two outings, but he’s righted the ship since with seven straight scoreless appearances out of the TinCaps bullpen. He’s fanned 12 and walked six over 11 1/3 innings in that time, reining in some of the control woes that marked his early High-A time.

Rockies: Sean Sullivan, RHP (No. 13)
The Rockies went the college pitching route with their first two picks in 2023, getting Chase Dollander in the first round and Sullivan in Round 2. Both have been pitching well for High-A Spokane, but Sullivan has been particularly effective of late. The southpaw has a 2.55 ERA over four starts this month, allowing just 19 hits over 24 2/3 innings (.198 BAA). He’s walked only two and struck out 27 in that span, and he has a ridiculous 50/3 K/BB ratio for the season.