Blas Castaño

Blas Castaño is a Dominican professional baseball pitcher for the Seattle Mariners of Major League Baseball. He made his MLB debut in 2025.

Career

New York Yankees

Castaño signed with the New York Yankees on June 1, 2018 and joined the Dominican Summer League Yankees that summer. He made his stateside debut in 2019 with the rookie-level Gulf Coast League Yankees. Castaño did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.
Castaño returned to action in 2021 with the rookie-level Florida Complex League Yankees and Single-A Tampa Tarpons. In 10 appearances split between the two affiliates, he accumulated a 6/2 record and 4.17 ERA with 55 strikeouts across innings pitched. Castaño split the 2022 campaign between the High-A Hudson Valley Renegades and Double-A Somerset Patriots, pitching to a cumulative 5-9 record and 3.86 ERA with 103 strikeouts over 22 appearances.
Castaño spent the majority of the 2023 season with the Double-A Somerset Patriots, also making two appearances for the Triple-A Scranton/Wilkes-Barre RailRiders; in 17 outings for Somerset, he logged a 4-3 record and 4.76 ERA with 42 strikeouts. Castaño was released by the Yankees organization on August 8, 2023.

Seattle Mariners

On August 11, 2023, Castaño signed a minor league contract with the Seattle Mariners and spent the rest of the season with the Double-A Arkansas Travelers. Castaño split the 2024 campaign between Double-A Arkansas and the Triple-A Tacoma Rainiers. In 29 games for the two affiliates, he accumulated a 5–8 record and 4.38 ERA with 108 strikeouts across innings pitched. On November 4, 2024, the Mariners added Castaño to their 40-man roster to prevent him from reaching minor league free agency.
Castaño was optioned to Triple-A Tacoma to begin the 2025 season. In 10 appearances, he logged a 2-1 record and 3.43 ERA with 28 strikeouts across innings pitched. On May 23, 2025, Castaño was promoted to the major leagues for the first time.