The Hardball Times has a list of the ten worst endings to postseason games. Luckily the Braves only make the list for causing another team to have one of the worst endings (because everyone knows the Braves only like happy endings). Here is there description of the Braves walk-off in 1999 against the Mets in the NLCS:
Newly-installed relief pitcher Kenny Rogers immediately ran into trouble, allowing a leadoff double. When a sacrifice advanced the runner to third, Atlanta needed only two outs to bring their man the final 90 feet to clinch the pennant.
Recognizing this, Mets manager Bobby Valentine decided to strategize. He ordered Rogers to intentionally walk the next two batters, setting up the force at all the bases. That way they could force the runner on third to take off for home, even if he otherwise wouldn't have gone. Besides, a single ends the game anyway, so why not set up the force?
Well, there was one scenario this strategy overlooked: Rogers' inability to find the plate. Sure enough, with the bases loaded and the game tied in the bottom of the 11th inning, Rogers couldn't locate his pitches and walked Andruw Jones, ending one of the greatest games on a walk-off walk. This was a combination of self-defeating managing and pitching to end the game.