That would be speedy Scott Podsednik of the 2005 White Sox clubbing a walkoff homer. As you heard Joe Buck say -- if you watched the video -- it was his second homer of the postseason. Still, Podsednik hit zero home runs in 568 regular-season plate appearances. In his regular-season career, Podsednik hit just 42 homers in over 1,000 games (his 162-game average is six home runs).
And yet, in Game 2 of the 2005 World Series, Podsednik ended it with a home run, giving his club a 2-0 lead in the best-of-seven series.
The White Sox would go on to sweep the Astros, winning their first World Series championship since 1917 and helping to erase the alleged curse of the 1919 Black Sox scandal.