Diego Castillo (pitcher)

Diego Castillo (born January 18, 1994) is a Dominican professional baseball pitcher in the Minnesota Twins organization. He has previously played in Major League Baseball (MLB) for the Tampa Bay Rays and Seattle Mariners.

Minor leagues
Castillo signed with the Tampa Bay Rays as an international free agent on March 5, 2014. He made his professional debut that season with the Dominican Summer League Rays and spent the whole season there, going 3–3 with a 3.96 ERA in 25 innings. In 2015, he played for both the Hudson Valley Renegades and Bowling Green Hot Rods, compiling a combined 1–2 record and 3.03 ERA in 18 relief appearances. In 2016, he pitched with both Bowling Green and the Charlotte Stone Crabs, posting a combined 3–6 record and 2.98 ERA in 60.1 total innings pitched out of the bullpen. In 2017, Castillo played for the Montgomery Biscuits and Durham Bulls. He was named the Rays' minor league reliever of the year after posting a 2.76 earned run average (ERA) with 90 strikeouts and 15 saves in 71.2 innings pitched. The Rays added him to their 40-man roster after the season. He began the 2018 season with the Durham Bulls.

Major leagues
Castillo was promoted to the Tampa Bay Rays and made his debut on June 6, 2018. For the season, he split time between the bullpen and being one of the Rays' "opening" starters. Castillo threw $56 2/3$ innings over 43 games, going 4–2 over 11 starts. He finished the year with a 3.18 ERA, 65 strikeouts and 18 walks.

In 2019, Castillo was used as both a closer and opener. On June 23, he was put on the 10-day injured list with shoulder inflammation. He finished the season appearing in 65 games (6 starts). In $68 2/3$ innings, he recorded 81 strikeouts, 8 saves, and an ERA of 3.41. In the postseason, Castillo threw 2 shutout innings in the American League Wild Card victory the Oakland Athletics. He threw $3 2/3$ innings over three games (one start) in the American League Division Series, where the Rays lost to the Houston Astros in five games.

In 2020, Castillo was moved away from the opener role. On July 24, he went on paternity leave. Castillo collected 4 saves over 22 games, posting an ERA of 1.66 with 23 strikeouts and 11 walks. In the postseason, he was used in late innings consistently when the Rays had the lead. He pitched the final two innings of Game 5 of the ALDS against the New York Yankees, picking up the win after Mike Brosseau's 8th inning home run. In the American League Championship Series against the Astros, Castillo appeared in 7 games, going 1–0 with 2 saves and 2 holds. The first run he allowed was in Game 6.

On July 7, 2021, Castillo combined with Collin McHugh, Josh Fleming, Matt Wisler, and Peter Fairbanks to no–hit the Cleveland Indians. However, since the feat was achieved in a truncated seven–inning doubleheader game, it was not recorded as an official no-hitter.

Seattle Mariners
On July 29, 2021, the Rays traded Castillo to the Seattle Mariners for J. T. Chargois and Austin Shenton. He made 24 appearances for Seattle down the stretch, registering a 3-1 record and 2.86 ERA with 26 strikeouts and 2 saves in 22.0 innings pitched.

In 2022, Castillo made 59 appearances for Seattle, logging a 7-3 record and 3.64 ERA with 53 strikeouts and 7 saves in 54.1 innings of work. In 2023, Castillo struggled to a 6.23 ERA with 7 strikeouts in 8 appearances to begin the year. On May 1, 2023, he was removed from the 40-man roster and sent outright to the Triple-A Tacoma Rainiers. In 43 appearances for Tacoma, he went 5–5 with a 5.13 ERA and 50 strikeouts in $47 1⁄3$ innings pitched. On October 9, Castillo elected free agency.

Minnesota Twins
On December 18, 2023, Castillo signed a minor league contract with the Texas Rangers. He was released by the Rangers organization on March 27, 2024.

On March 29, 2024, Castillo signed a minor league contract with the Minnesota Twins. In 18 games for the Triple–A St. Paul Saints, he recorded a 2.50 ERA with 22 strikeouts and 5 saves across 18 innings pitched. On May 28, the Twins selected Castillo's contract, adding him to their major league roster. In five appearances for Minnesota, he recorded a 2.57 ERA with three strikeouts across seven innings of work. Castillo was designated for assignment following the promotion of Jay Jackson on June 12. He elected free agency on June 16. On July 3, Castillo re–signed with the Twins on a minor league contract.