The biggest comeback in MLB Playoff history occurred in 2004. You, and the next 100 years of sports fans, know that because it was the Boston Red Sox and they've perfected the art of victimized boasting. The squad that came back from down 3-0 to the "rival" Yankees were rumored to pregame for the biggest contests of their lives by taking shots of Jack Daniels (or Mama Juana if you believe Pedro). They took shots prior to Games 6 and 7 of the ALCS and then every single game of the 2004 World Series against St. Louis.
The result? A perfect 6-0 run that culminated with their first title in 86 years. Okay, so technically they weren't drunk but we're going to claim that taking the edge off capped the insufferable streak; and perhaps if Calvin Schiraldi was tanked he wouldn't of choked away Game 6 and made Bill Buckner Boston's greatest villain since Whitey Bulger.