Castro and the Nationals agreed Wednesday on a minor-league contract that includes an invitation to big-league spring training, Mark Zuckerman of MASNSports.com reports.
The 27-year-old reliever will get the opportunity to compete for a spot in the Nationals' Opening Day bullpen after he made 12 MLB appearances for the Guardians in 2022, logging a 7.43 ERA and 2.17 WHIP in 13.1 innings. In the likely event that he falls short in his bid for a roster spot with the big club, Castro is expected to begin the 2023 season with the Nationals' Triple-A affiliate in Rochester.