By DZ. Filed June 5, 2025.
The two headlines from this monthly update both come out of Italy –- one at the top of the list and one at the bottom. Samuel Aldegheri, who in 2024 became the first Italian born-and-developed pitcher in the Major Leagues, received a recall to MLB a few days ago. Meanwhile, the first of several expected 2025 European signings was made official when 18-year-old lefty Giacomo Taschin joined the Blue Jays’ organization. Amongst several debuts, new signing Keegan Pieternella has suited up for the first time, also with Toronto.
On the flip side, Netherlands Sem Robberse needs elbow surgery and will miss the rest of the year. Countryman Connor Prins has yet to pitch this year and is on the long-term injured list as well.
Finally, back to the good news: Peter Bonilla (Spain), Tim Fischer (Germany), Mattias LaCombe (France), and Williams Wong (Italy) all made their U.S. professional debuts. LaCombe’s activation was particularly good news after sitting out the last two seasons following his drafting from Cochise College (Ariz.). The other three move stateside after multiple seasons in the Dominican Summer League.
All players who grew up within European leagues or development systems are included. If someone is missing, shout at us!
Key
Name (age*), organization, country, team.
*Age is as of Sept 1, 2025 (playing age this season).
Team Prospect Rankings: BA (Baseball America): #; FG (Fangraphs): #; MLB (MLB.com): #.
“NR” denotes not ranked (only included for players listed in other rankings).
MLB (2)
Samuel Aldegheri (23), Los Angeles Angels. Italy. BA: 3; FG: 5; MLB: 5.~
Aldegheri is 2-2 with a 4.34 ERA through nine Double-A games, and was rewarded with a June 2 recall to the big leagues. He has since made his 2025 MLB debut (after four appearances in 2024) with two scoreless innings with one walk, one hit, and one strikeout. In his 47.2 minor league innings, he had 48 strikeouts, 30 free passes, and 42 hits allowed for a 1.45 WHIP.
Max Kepler (32), Philadelphia Phillies. Germany.
Kepler hit .188 for the month of May with three home runs. He struck out 22 times and walked in eight plate appearances. For the season he’s hitting .221/.307/.387 with six home runs and 12 doubles, which amounts to slightly below average production after the slump.
Triple-A (3)
Adam Macko (24), Toronto Blue Jays. Slovakia/Ireland. Buffalo Bisons. BA: 20; FG: 12; MLB: 15.
Macko technically remains on a rehab assignment (these are allowed up to 30 days) from Triple-A Buffalo, despite all five of his appearances thus far taking place with the Florida Coast League rookie level Blue Jays. He has 26 strikeouts and a mere three walks in 17.1 innings, with a 3.63 ERA, 0.98 WHIP, and 0-1 win-loss record.
Ernesto Martinez, Jr. (26), Milwaukee Brewers. France. Nashville Sounds. BA: NR; FG: NR; MLB: 30.
The rising first base prospect returned from a 17-day stint on the injured list on May 8 with mixed results, hitting .195 with a .317 slugging percentage, but also drawing 14 walks to contribute with a .411 on-base average. He has not played since May 28. Overall, Martinez is hitting .262 with a .398 on base percentage. He has walked 23 times while striking out 26 and has tallied seven extra base hits. Martinez has hit at every level, with a career .263 batting average and .365 OBP.
Sem Robberse (23), St Louis Cardinals. Netherlands. Memphis Redbirds. BA: 20; FG: NR; MLB: 14.Robberse made four starts before going on the injured list on April 21. Unfortunately, not long after that start and shortly after our list published last month, it was announced that Robberse requires Tommy John surgery on his throwing elbow. That will typically shut down a pitcher for 12-15 months, ending his 2025 season and cutting into a significant portion of 2026 as well. Over his six-year minor league career, he has a 4.08 ERA and 425 strikeouts in 439.1 innings, which have come in 97 games, 90 starts.
Double-A (2)
Alessandro Ercolani (21), Pittsburgh Pirates. San Marino. Altoona Curve. BA: 21; FG: Hon. Men.; MLB: NR.
In 24 innings across his last six starts, Ercolani has allowed 22 hits, struck out 18, and walked five. He’s in the regular rotation, but only once has he been allowed to exceed four innings pitched. For the full season, he has a 4.79 ERA in 35.2 innings with a 1.18 WHIP.
Arij Fransen (24), Cincinnati Reds. Netherlands. Chattanooga Lookouts. BA: NR; FG: Hon. Men.; MLB: NR.
Fransen is pitching in relief in 1-to-2 inning stints. As of June 1, his season ERA was 2.01, despite giving up five runs (two earned) in his last inning of May. He retains a strong 2.96 ERA after another four runs (three earned) crossed the plate in his first appearance of June. He’s pitched 24.1 innings, striking out 25, and walking 12.
High-A (2)
Omar Hernandez (23), Kansas City Royals. Spain. Quad Cities River Bandits.
In 25 games played across the first two months of the season, Hernández is nearly matching his career numbers to date with a .227 BA (.222 career), .269 OBP (.289), and .284 slugging percentage (.297). He has five doubles and has six stolen bases in seven attempts.
Kay-Lan Nicasia (25), Milwaukee Brewers. Netherlands. Wisconsin Timber Rattlers.
Nicasia has two hits, three runs scored, and a stolen base in four games since returning from the IL. In 45 at bats for the season, he is hitting .178 with three home runs.
Single-A (1)
Yannic Walther (21), Milwaukee Brewers. Germany. Carolina Mudcats.
Walther is hitting .148 with a home run in 66 at bats, while maintaining a .333 on-base percentage. He has nine hits and 16 walks, with 26 strikeouts.
Rookie League, U.S. Complex Leagues (8)
Peter Bonilla (20), Los Angeles Dodgers. Spain. ACL Dodgers.
fter persevering for three seasons in the Dominican and compiling an ERA just over two, Bonilla made his U.S. debut. He has eight appearances for a total of 10.1 innings, striking out 13, and walking eight with an equal number of hits allowed. He is 0-1 with a 4.35 ERA. His career record stands at 13-2 with a 2.51 ERA.
Tim Fischer (20), Los Angeles Dodgers. Germany. ACL Dodgers.
Fischer moved from the DSL to the Arizona League on May 18, and he has since made his first five U.S. appearances. In three innings, he has one strikeout, four walks, and four hits allowed.
Brandon Herbold (22), Kansas City Royals. Netherlands. ACL Royals.
Herbold has three scoreless innings in three appearances thus far. He has punched out six, walked three, and allowed only one hit.
Mathias LaCombe (23), Chicago White Sox. France. ACL White Sox.
Despite being drafted in the summer of 2023 out of a US junior college, LaCombe has only now debuted due to a series of injuries. The right-hander has shown few signs of rust—in five games and 15 innings, he has registered 25 strikeouts, five walks, and five hit batters, allowing 13 hits and eight earned runs.
Connor Prins (21), Seattle Mariners. Netherlands. ACL Mariners.
The Dutch pitcher has been on the 60-day injured list all season and has not pitched since late-July 2024.
Dominic Scheffler (21), Cincinnati Reds. Switzerland. ACL Reds.Scheffler was in Single-A before his demotion in mid-May. Since returning to Arizona, the Swiss lefty has hit the reset button, tossing four scoreless innings with seven strikeouts and zero walks. In his eight games with Daytona before that, his ERA was 20.86 with a whopping 21 walks and hit batters in 7.1 innings.
Gijs van den Brink (20), Kansas City Royals. Netherlands. ACL Royals.
Van den Brink made a single appearance of two scoreless innings on May 6 and, despite remaining on the active roster, has not pitched since. He gave up one hit and one walk while recording six outs.
Williams Wong (19), Texas Rangers. Italy.
Wong was promoted May 13, but has only two game appearances and one official at bat so far in the U.S. He has walked three times and struck out once in four plate appearances.
Rookie League, Dominican Complex Leagues (4)
The Dominican rookie leagues officially opened their season June 2, so we do not have any statistics just yet.
Paul Hoff (18), Milwaukee Brewers. Germany. DSL Brewers 2.
Keegan Pieternella (17), Toronto Blue Jays. Netherlands. DSL Blue Jays Red.
The most recent addition to the list, Pieternella officially signed on Jan. 18, though his signing flew under the radar until more recently. The Dutch catcher has hits in his first two games, going 2-for-5 with a walk and a strikeout thus far. See our article on his signing here [link].
Filippo Sabatini (18), Philadelphia Phillies. Italy. DSL Phillies White.
Giacomo Taschin (18), Toronto Blue Jays. Italy. DSL Blue Jays Blue.
Taschin signed with Toronto earlier this spring. For the full story, read our article on his signing [link].
Editor’s Note
Jurrangelo Cijntje has beenincluded in previous updates since the Seattle Mariners drafted him last summer. Although he was born in the Netherlands to a long-term of the Honkbal Hoofdklasse, the younger Cijntje did not take up baseball until moving to Curaçao. Listed on two Top 100 lists (Fangraphs and Baseball Prospectus), the switch-pitcher is aiming to become the 18th player and fourth pitcher from the Dutch Caribbean island to make the majors. He would also become the third Amsterdam-born player to reach the bigs.
Note: This article was revisted to include Pieternella, who was originally left off the list.