Castro walked one and struck out two in a scoreless ninth inning to record his first save of the season in Saturday's 5-3 win over the Nationals.
Cole Sulser worked the eighth inning and picked up the hold, while Mychal Givens didn't pitch at all, adding yet another wrinkle to manager Brandon Hyde's late-inning bullpen management. Castro has certainly earned a high-leverage role, posting a 0.00 ERA and 10:2 K:BB through his first 7.1 innings on the year, so this may not be the last time he gets the call in the ninth for the O's.