Arroyo also got his first and only championship title when the Red Sox won the World Series against the St. Louis Cardinals. Arroyo made two starts and four relief appearances in the postseason, compiling a 0–0 record with two holds and a 7.82 ERA for the 2004 World Series champion Red Sox. A memorable and controversial play occurred involving Arroyo during Game 6 of the 2004 American League Championship Series, when Alex Rodriguez knocked away the ball from Arroyo's glove while he attempted to apply a tag. The umpires reversed the ruling that Rodriguez was safe, forcing Derek Jeter to return to first base and calling Rodriguez out on the play for runner interference.