Inspired by a similar post in the Red Sox forum. I vote for Johnny Damon’s double steal in the 2009 World Series, which swung momentum in the game and the series. There must be others, although the Yankees were never known for base-stealing. Perhaps their most famous attempt was Babe Ruth getting thrown out trying to steal second in the 1926 World Series.
From MLB.com:
Johnny Damon, Yankees
2009 World Series Game 4 at Phillies
Trailing the Yankees two games to one in the World Series, the Phillies tied up Game 4 on Pedro Feliz’s two-out solo homer in the bottom of the eighth inning and were one out away from bringing their offense back to the plate in the ninth. That's when Damon stepped into the batter's box and changed the course of the game.
After lacing a single off Brad Lidge, Damon immediately took off on the next pitch and stole second with ease, then realized that nobody was covering third base due to Philadelphia’s shift on Mark Teixeira. Damon popped up from his slide and took third as well, completing a stunning double steal. Two batters later, Damon scored the go-ahead run on Alex Rodriguez’s double, and New York took a 3-1 series lead en route to its 27th World Series title.
From MLB.com:
Johnny Damon, Yankees
2009 World Series Game 4 at Phillies
Trailing the Yankees two games to one in the World Series, the Phillies tied up Game 4 on Pedro Feliz’s two-out solo homer in the bottom of the eighth inning and were one out away from bringing their offense back to the plate in the ninth. That's when Damon stepped into the batter's box and changed the course of the game.
After lacing a single off Brad Lidge, Damon immediately took off on the next pitch and stole second with ease, then realized that nobody was covering third base due to Philadelphia’s shift on Mark Teixeira. Damon popped up from his slide and took third as well, completing a stunning double steal. Two batters later, Damon scored the go-ahead run on Alex Rodriguez’s double, and New York took a 3-1 series lead en route to its 27th World Series title.