The New York Mets acquired left-handed reliever Jose Castillo from the Arizona Diamondbacks on May 15 in exchange for cash considerations. Castillo, 29, had been designated for assignment by Arizona earlier in the week for top prospect Jordan Lawlar. To make room on the 40-man roster, New York designated right-hander Kevin Herget for assignment.
We have acquired LHP Jose Castillo from Arizona in exchange for cash considerations.
In a corresponding move, RHP Kevin Herget has been designated for assignment.
— New York Mets (@Mets) May 16, 2025
Why Did the Diamondbacks Move On From Jose Castillo?
Castillo made five relief appearances for Arizona this season, posting an 11.37 ERA over 6.1 innings. He gave up 10 hits, eight earned runs, and three home runs, with a 3-to-3 strikeout-to-walk ratio. Opponents slashed .370/.419/.778 off him.
Castillo throws from a low arm slot and leans heavily on his slider (61.5 percent usage), which averages 84.4 mph and induces a 33.3 percent groundball rate. His sinker (93.3 mph) has been crushed this season.
The Diamondbacks moved on after Kendall Graveman returned from the IL.
Injuries Following Promising 2018 Rookie Campaign
The Venezuelan lefty hasn’t replicated his promising 2018 rookie campaign with San Diego, when he posted a 3.29 ERA and 12.2 K/9 in 38.1 innings.
Since then, Castillo has made just eight big league appearances over the next six seasons combined. He entered 2025 with a career 5.21 ERA and a WHIP of 1.18 across 46.2 innings.
Castillo underwent left flexor tendon surgery in 2019 and missed the entire season. In 2020, he suffered a left lat strain in summer camp and was shut down again. He attempted a comeback in 2021 but suffered another elbow strain and didn’t pitch in affiliated ball that season. He returned to the Padres’ system in 2022 and made one appearance at the big-league level, then bounced between Triple-A and brief stints with San Diego and Miami in 2023 before signing a minor league deal with Arizona this past winter.
Why Did the Mets Acquire Jose Castillo?
The Mets have been short on left-handed relievers since losing Danny Young and A.J. Minter to season-ending injuries. With the addition of Castillo, they now have two lefties in the bullpen — Castillo and Genesis Cabrera. Because Castillo is out of minor league options, the Mets will need to keep him on the big-league roster or risk losing him. To make room, Dedniel Nunez — who can still be sent to the minors — is likely to be optioned once Castillo arrives.
To clear space, the Mets designated Kevin Herget for assignment. The 33-year-old righty was claimed off waivers from Milwaukee last offseason and had logged a 2.87 ERA over 15.2 innings at Triple-A Syracuse. Herget made one MLB appearance for the Mets this year, allowing two runs in a single inning of work. He has been outrighted twice previously and will have the right to elect free agency if he clears waivers.
Does Jose Castillo have WBC Experience?
Yes. Castillo also has international experience, having pitched for Venezuela in the 2017 World Baseball Classic. He closed out a wild 11-10 win over Italy with a perfect ninth inning, notching a save in what remains one of the most memorable outings of his early career.
Padres prospect Jose Castillo recorded the save in Team Venezuela's win over Italy 💪🇻🇪 #WBC2017 https://t.co/zjxmww2rwP
— San Diego Padres (@Padres) March 12, 2017
Jose Castillo has had multiple stints with Navegantes del Magallanes in the Venezuelan Winter League (LVBP). Most recently, during the 2023–24 season, he appeared in 13 games, recording a 0–1 record with a 3.14 ERA over 14.1 innings, along with 16 strikeouts and a 1.26 WHIP. In 2016 and 2017 he also pitched for Magallanes in limited appearances.
🔥⚾ José Castillo seguirá con el @Magallanes_bbchttps://t.co/hRSIhNAdYV#ConTodoYMás | #LVBP pic.twitter.com/bjVdhpteV4
— #NuestroBeisbol ⚾️🇻🇪 (@LVBP_Oficial) November 24, 2023
Castillo will need to significantly turn around his career to enter the national team conversation for the 2026 World Baseball Classic. Venezuela will also have to evaluate how they will build out both their starting rotation and bullpen for next March, with arms like Pablo Lopez, Jesus Luzardo, Ranger Suarez, Martin Perez, Eduardo Rodriguez, Edgardo Henriquez, Brusdar Graterol, Jose Ruiz, German Marquez, Jose Butto, Robert Suarez, Jose Alvarado, and Luis Garcia either returning from their 2023 roster or potentially joining the national team for the first time.
For more Venezuelan WBC roster news and projections, check World Baseball Network’s coverage of Migue Cabrera joining the 2026 WBC Roster as a hitting coach.
(AP Photo/Matt Slocum)
