Hottest pitching prospect in each system

July 27th, 2023

This time of year is often described as the dog days of summer, especially when looking at the long grind of a Minor League baseball season.

It's a time when young pitchers frequently hit a wall as they're still learning how to handle the rigors of a full year's workload.

Not so with this lot. The 30 pitchers highlighted below have all either ignored that wall or are pushing through it, putting up some eye-popping numbers over the last month.

AMERICAN LEAGUE EAST

Orioles: Alex Pham, RHP (not ranked among Top 30)
A 19th-round Draft pick in 2021 out of the University of San Francisco, Pham was largely a reliever in college and at the outset of his pro career. Given a chance to start, he's made it to Double-A and has a 2.14 ERA and 11.5 K/9 rate for the season. That includes a 1.80 ERA and .143 BAA in his last four outings with Bowie (1.35 ERA in five outings since his promotion), with a low-90s fastball, a good curve and a cutter.

Blue Jays: Sem Robberse, RHP (No. 7)
One of Toronto's two Futures Game representatives, the 21-year-old Dutchman is settling into a nice groove with Double-A New Hampshire. Robberse owns a 1.33 ERA and 0.98 WHIP over his last four starts (20 1/3 innings) with the Fisher Cats. While his 15 strikeouts haven't exactly popped in that span, his 49 percent groundball rate has certainly helped play a large role in keeping the other numbers low. Armed with a low-90s fastball and above-average breaking ball, Robberse is still plenty young for Double-A and is still growing into his own.

Rays: Trevor Martin, RHP (No. 30)
Tampa Bay's 2022 third-rounder has fanned at least eight batters in each of his last three starts for Single-A Charleston and has a 1.91 ERA with 36 strikeouts and only five walks over his last five outings (28 1/3 innings). Martin has good velocity in the mid-90s but lacked above-average secondaries entering 2023, although he's overpowering Carolina League hitters as a former college arm. A move to High-A Bowling Green can't be far off.

Red Sox: Angel Bastardo, RHP (No. 29)
Signed for just $35,000 out of Venezuela in 2018, Bastardo has become one of Boston's better pitching prospects while working with a mid-90s fastball that highlights a four-pitch mix. He has posted a 1.13 ERA with a .161 opponent average and 36/5 K/BB ratio in 24 innings during four High-A starts this month. He ranks second in the South Atlantic League in strikeouts (119 in 87 2/3 innings) and third in opponent average (.202).

Yankees: Drew Thorpe, RHP (No. 6)
A second-round pick out of Cal Poly in 2022, Thorpe is thriving with an outstanding changeup and advanced command of his fastball and slider during his first full pro season. He's making a run at the High-A South Atlantic League pitching triple crown, leading in wins (10) and strikeouts (124 in 99 1/3 innings) and ranking second in ERA (2.02). He has been even better as of late with a 1.04 ERA, .155 opponent average and 45/9 K/BB ratio in his last five starts (34 2/3 innings).

AMERICAN LEAGUE CENTRAL

Guardians: Will Dion, LHP (No. 30)
Dion stands out most with his strike-throwing and his solid changeup, and he's on a roll with a 1.96 ERA, .224 opponent average and 20/7 K/BB ratio in his last four starts (23 innings) in Double-A. The 2021 ninth-rounder from McNeese State leads the system with a 2.63 ERA between High-A and Double-A.

Royals: Ben Kudrna, RHP (No. 2)
After opening the year back with Single-A Columbia, Kudrna struck out 16 (including a career-high 10 on June 29) over his final two starts with the Fireflies before finally earning his move to High-A Quad Cities last week. The 20-year-old right-hander didn't skip a beat, scattering three hits and two walks over six scoreless innings in his Midwest League debut last Thursday. His fastball, slider and change all flash above-average, and showing that level of stuff consistently remains a focus in the 2021 second-rounder's second full season.

Tigers: Tyler Mattison, RHP (No. 24)
The Bryant product hasn't allowed a run in his last 12 appearances between High-A West Michigan and Double-A Erie and has struck out 29 over 16 1/3 innings in that span. He's also holding batters to just a .077 average in those dozen outings while working out of the bullpen. Shoulder issues last year have moved Mattison to the bullpen in 2023, and he works well north and south out of an over-the-top delivery in that role.

Twins: C.J. Culpepper, RHP (No. 26)
It's hard to be much better than Culpepper has been over the last month. The right-hander hasn't allowed a run since June 13, tossing 22 scoreless frames over his last four starts, three of which came following a promotion to High-A Cedar Rapids. He's given up just 10 hits and three walks (0.59 WHIP) while striking out 17 in that span.

White Sox: Matthew Thompson, RHP (No. 13)
Thompson hasn't lived up to expectations since signing for $2.1 million as a Texas high schooler taken in the second round of the 2019 Draft, but he's in the midst of his best season yet. He has compiled a 2.11 ERA, .187 opponent average and 18 strikeouts in his last 21 1/3 innings over four Double-A starts. He owns a 92-97 mph fastball, but his best pitch is a 78-82 mph curveball with quality depth when he stays on top of it.

AMERICAN LEAGUE WEST

Angels: Caden Dana, RHP (No. 9)
The Angels' decision to give Dana $1.5 million in Round 11 of the 2022 Draft seems to be paying off. He's just 19 and already in High-A, adjusting to the new level just fine. Over his last three starts in this period, Dana has allowed just two earned runs (0.96 ERA), 11 hits and five walks (0.86 WHIP) in 18 2/3 IP, striking out 25. The 6-foot-4 right-hander has a 3.56 ERA, .206 BAA and 11.7 K/9 rate overall in his first full season of pro ball.

Astros: Colton Gordon, LHP (No. 8)
Gordon had Tommy John surgery two months before the Astros drafted him in 2021's sixth round out of Central Florida, yet he quickly has emerged as one of their top pitching prospects. He imparts impressive carry on an 89-94 mph fastball and throws a ton of strikes, enabling him to pace the system in ERA (3.28) and strikeouts (109 in 85 innings). In his last four Double-A starts, he has put up a 1.89 ERA, .177 opponent average and 30/7 K/BB ratio in 19 innings.

A's: Joey Estes, RHP (No. 19)
Estes, who came to the A's via the 2022 Matt Olson deal, has been solid all year, with a 3.35 ERA and .218 BAA as a 21-year-old in Double-A for the first time. The last 30 days were a continuation of that, as the right-hander posted a 3.07 ERA, 1.16 WHIP and .234 BAA over five starts spanning 29 1/3 innings. He continues to fill up the strike zone (71 percent strike rate) while walking just 2.7 BB/9 for the season.

Mariners: Jeter Martinez, RHP (No. 30)
Signed just this past January as part of the 2023 international class, Martinez is wasting no time in impressing during his pro debut. He's made four appearances in the Dominican Summer League over the last 30 days, allowing just three earned runs (1.37 ERA) on only three hits in 19 2/3 IP. He has walked 11, though that still is just a 0.71 WHIP since he's been so hard to hit, and he's whiffed 25 in that span. He has a 1.08 ERA and 11.9 K/9 rate for the year.

Rangers: Antoine Kelly, LHP (No. 23)
Kelly's quality stuff attracted both the Brewers (who drafted him in 2019's second round out of Wabash Valley, Ill., CC) and the Rangers (who acquired him in the Matt Bush trade last July), but he often has struggled to harness it. He's doing a better job of throwing strikes with his mid-90s fastball and sweeping mid-80s slider lately, sporting a 0.00 ERA, .194 opponent average and 11/1 K/BB ratio in his last nine relief appearances (10 innings) in Double-A.

NATIONAL LEAGUE EAST

Braves: Luis De Avila, LHP (No. 26)
A Minor League Rule 5 pick after the 2021 season, De Avila led the South Atlantic League in ERA in 2022. He's continued to thrive while turning 22 in Double-A, and his 3.05 ERA over his last four starts is right in line with his 3.04 mark for the year, putting him third in the Southern League. He's continued to miss bats all year (9.58 K/9 during this period on par with his 9.56 season rate) and get groundball outs (1.71 GO/AO for the season).

Marlins: Jake Eder, LHP (No. 4)
A Vanderbilt product, Eder went from the fourth round of the 2020 Draft to Double-A to the Top 100 Prospects list in the span of a year before blowing out his elbow in August 2021. After recovering from Tommy John surgery, he dealt with a fractured left foot this spring and finally returned to the mound in June. He's regaining his plus fastball and curveball and has recorded a 4.12 ERA with a .222 opponent average and 26 strikeouts in 19 2/3 innings during his last four Double-A starts.

Mets: Tyler Stuart, RHP (Not ranked among Top 30)
Last year's sixth-rounder out of Southern Miss isn't ranked among New York's Top 30 now but certainly will be after the August update. The 6-foot-9 right-hander's 1.62 ERA between High-A and Double-A leads all full-season Minor League qualifiers, and that comes after he hasn't allowed more than two earned runs in any of his 16 starts in his first full season. Stuart debuted with Binghamton on July 15 and has allowed only three earned runs in 13 innings (2.08 ERA) over his first two Double-A starts. Stuart has great command for his size, can touch the mid-90s with his heater and leans heavily on his slider.

Nationals: Andry Lara, RHP (No. 14)
Lara has allowed one or zero earned runs in five of his last six outings for High-A Wilmington, and after being particularly vulnerable to the long ball earlier in the season, it's a good sign that he's allowed only one dinger in that span, helping result in a 2.92 ERA. If you want to blame Wilmington's pitcher-friendly conditions for those numbers alone, it should be noted that the six starts were split evenly between home and road. Lara has long been about projection more than present stuff with a mid-90s fastball and fringy slider and change, but this run gives more optimism about his starting chances.

Phillies: Griff McGarry, RHP (No. 4)
McGarry missed the first chunk of the season with an oblique injury and after using May to shake off the rust and build himself up, he's been dominant over the last two months with Double-A Reading. Over his last four starts spanning 22 1/3 IP, the right-hander has a 2.01 ERA and 1.03 WHIP. That includes an improved 4.03 BB/9 rate and his usual 12.9 K/9 rate, while keeping hitters to a .167 batting average.

NATIONAL LEAGUE CENTRAL

Brewers: Logan Henderson, RHP (No. 22)
Elbow surgery limited Henderson to only 13 2/3 innings during the regular season last year. The 2021 fourth-rounder has been both healthy and productive of late with a 1.80 ERA, 24 strikeouts, five walks and a .108 average-against in his last four starts for Single-A Carolina. The biggest news might be that he cleared six innings for the first time as a pro last time out on July 22, one start after he threw a career-high 96 pitches a week earlier.

Cardinals: Pete Hansen, LHP (No. 11)
The 2022 third-rounder out of Texas didn't exactly get an aggressive assignment to Single-A Palm Beach and is now pitching like he needs to see High-A Peoria soon. The southpaw has lasted at least six innings in three of his last four starts and has a 3.04 ERA and 0.89 WHIP with 24 strikeouts over 23 2/3 innings in that span. He lacks velocity on his 88-91 mph fastball, but his low-80s sweeping slider and mid-80s change has certainly helped the whiffs coming in the Florida State League.

Cubs: Kohl Franklin, RHP (No. 24)
Franklin has been one of the Cubs' more promising mound prospects since turning pro as a 2018 sixth-rounder out of an Oklahoma high school, but he also has battled injuries and inconsistency. The nephew of former All-Star closer Ryan Franklin has been better of late and continues to show the potential for a solid four-pitch mix. He has a 1.72 ERA with a 21/7 K/BB ratio in his last four starts over 15 2/3 innings in Double-A.

Pirates: Michael Kennedy, LHP (No. 19)
The Pirates went over slot ($1 million) to sign Kennedy as their fourth-rounder in 2022, and the upstate New York high school product didn't make his official pro debut until this summer in the Florida Complex League. While he didn't throw well in his most recent start on Tuesday, he was showing glimpses of his promise over his previous four outings (2.57 ERA, .177 BAA, 12.2 K/9 over 14 IP).

Reds: Julian Aguiar, RHP (No. 27)
A junior college draftee taken in the 12th round of the 2021 Draft, Aguiar has pitched his way from High-A to Double-A, earning the promotion earlier this month. During this period, he's posted a 2.57 ERA and 1.10 WHIP with a ridiculous 26/3 K/BB ratio over 21 IP. For the year, the right-hander has a 2.13 ERA, 1.03 WHIP, 10.1 K/9 rate and .191 BAA.

NATIONAL LEAGUE WEST

D-backs: Dylan Ray, RHP (No. 22)
Ray entered his June 29 start for High-A Hillsboro with a 5.77 ERA on the season. That's now down to 4.11 after a dominant four-outing stretch in which he's tossed three quality starts. Since June 29, Ray owns 0.75 ERA and 0.92 WHIP with 26 strikeouts in 24 innings. His 92-95 mph fastball has good carry up in the zone, and he can keep hitters off with a plus mid-80s slider.

Dodgers: Landon Knack, RHP (No. 17)
Expected to move quickly after LA drafted him in 2020's second round out of East Tennessee State, Knack was hampered by hamstring injuries in his first two full pro seasons. Healthy again, he tops the Dodgers system in ERA (2.72) and K/BB ratio (4.4) while featuring a tight mid-80s slider as his best pitch. In his last four Triple-A starts, he has posted a 3.26 ERA with a 19/4 K/BB ratio in 19 innings.

Giants: Hayden Birdsong, RHP (No. 26)
Birdsong flew under the radar before the Giants drafted him in 2022's sixth round out of Eastern Illinois, but that's no longer the case now that he tops their system in ERA (2.57) and strikeouts (110 in 73 2/3 innings). Armed with a mid-90s fastball and upper-70s curveball, he has compiled a 1.08 ERA, .133 opponent average and 34/4 K/BB ratio in 25 innings during his last five outings in High-A.

Padres: Jackson Wolf, LHP (No. 16)
We're technically only supposed to consider Minor League results for this story, so we'll talk about the period that led to Wolf's solid Major League debut last Saturday. Before that outing, the 6-foot-7 southpaw had a 2.79 ERA with 30 strikeouts and six walks over his last five starts (29 innings) with Double-A San Antonio before that callup in which he skipped right over Triple-A El Paso. Wolf lacks stellar velo (averaging only 88.9 mph on his fastball in his MLB bow), but his mid-70s slider and low-80s changeup offer looks that can keep hitters from getting comfortable.

Rockies: Case Williams, RHP (No. 21)
Williams' first full season in Double-A has been uneven, including a stint on the injured list, but he's aiming to finish it off strongly. In his four starts over the last 30 days, he's posted a 2.82 ERA and 0.99 WHIP, giving up just 18 hits (.220 BAA) and four walks over 22 1/3 IP while striking out 20. That's allowed him to lower his ERA from 7.49 in mid-June to just under 6.00 as his command in and out of the strike zone has improved.