That has happened only once in MLB and that was in 2004 when the Red Sox defeated the Yankess, 4 games to 3, in the ALCS after being down 3 games to 0.
Four Major League Baseball teams have won the World Series after being down 3 games to 1 after the first four games: the 1925 Pittsburgh Pirates (defeating the Washington Senators), the 1958 New York...
The Boston Red Sox came back down 0-3 in the series against the New York Yankees to win the series in 2004 in the ALCS. It is the only time this has ever happened in MLB history.