sentences:  Major League Baseball, the National Basketball Association, and the National Hockey League are three professional sports that feature best-of-seven games series in their playoffs.Coming back to win a seven-game series when down by three games has only been accomplished by four National Hockey League teams and only one Major League Baseball team in the history of the MLB, NBA, and NHL.The 1942 Toronto Maple Leafs (NHL) came back from being down by three games to the Detroit Red Wings to win the 1942 Stanley Cup.