What is the fine-grained topic of the following text: Whistling to the tunes of Sister Sledge's "We Are Family", the 1971 Pittsburgh Pirates danced their way to a World Series title behind the star play of Roberto Clemente, Willie Stargell and co. in the club's very first season at Three Rivers Stadium, winning a thrilling 7-game series over the Baltimore Orioles. Only return the topic.
1971 Pittsburgh Pirates' World Series victory