Mets acquire lefty reliever in trade with Diamondbacks

Castillo, 29, has made 45 career MLB appearances, with all but eight coming during his rookie year with the San Diego Padres in 2018. The 6-foot-6 lefty posted a 3.29 ERA and 0.91 WHIP with 52 strikeouts in 38.2 innings as a rookie, but various injuries have limited his playing time since.

In 2019, Castillo began the season on the 60-day injured list due to a left flexor strain. He injured his left middle finger in his first outing back, which ended his season.

He missed all of 2020 with a left lat strain and a torn ligament in his hand, and a few days after exiting a simulated game in early March 2021 with forearm tightness, it was announced he would need Tommy John surgery.

Castillo made 21 appearances for the Diamondbacks’ Triple-A affiliate in 2024 and re-signed with the organization on a minor league deal this past winter. He was called up to the majors at the beginning of May and, in five appearances, allowed eight runs on 10 hits — including three home runs — over 6.1 innings. Arizona designated him for assignment on Monday.

Castillo utilizes three pitches: a 93 mph sinker, a four-seamer at the same speed, and an 84 mph slider — his most frequent offering. According to Statcast, his slider generated a 40.8% whiff rate and a +7 run value during his rookie season, but it has not been nearly as effective during his limited MLB action in 2025.

Since Castillo is out of minor league options, he appears primed to spend at least some time in the Mets’ big league bullpen. Currently, the only other left-handed reliever on their active roster is Génesis Cabrera, who was called up after the Mets lost both Danny Young and A.J. Minter to season-ending injuries.

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New York recently re-signed 36-year-old veteran Brooks Raley, who served as their top left-handed reliever before undergoing Tommy John surgery last May. In 74 appearances with the team, he posted a 2.48 ERA, 1.20 WHIP, and a 10.2 K/9 rate.

Raley is not expected to be ready for a major league return until late June at the earliest. Until then, the Mets will see what production they can get from their other left-handed options.