I intended to write an article debunking the popular theory that "momentum" is an important factor in the postseason. Of all the evidence we have of momentum meaning bupkus, people still yell about it. It's a classic example of people not letting their beliefs be affected by reality. Everyone said that the Astros were "finishing" heading into Game 6 of the NLCS, because the Cardinals had the momentum on their side. Then the Astros won, and everyone was proven wrong. I'm still waiting for all the "Hey, I was wrong" articles. I'll be waiting for a while.
I was going to write this article, but then Brian Gunn over at The Hardball Times beat me to it. So, Mr. Gunn's fine article notwithstanding, I'll do the best I can to dispel the myth of "momentum." I'll look at the most recent examples, since they're the ones you all remember.
2004 ALCS: Red Sox .vs. Yankees
Remember this one? The Yankees won the first three games of the ALCS. Not only that, but their Game 3 victory was an absolute skunking, 19-8, at Fenway Park. If ever a team had momentum in a series, the Yankees had it last year. And that momentum got them diddly-squat, as the Red Sox won anyway.
2003 NLCS: Cubs .vs. Marlins
If you'll recall, the Cubs took a 3-games-to-1 lead in this Series. If they had won, everyone would have said that the Cubs were "destined" to win, and that the Marlins couldn't overcome their momentum. But, of course, that's not what happened. Steve Bartman caught the ball, and the Cubs lost. No one points out that someone (not Steve Bartman) stood on the pitcher's mound and allowed those 8 runs, and someone was doing a good job of hitting to score them. But Bartman gets the blame, because it makes for a good story. Thus is the negative influence of journalism on baseball.
2001 World Series: Diamondbacks .vs. Yankees
The Yankees, down 2 games to 1 in New York, were losing Game 4 when Tino Martinez hit a game-tying homer and Derek Jeter hit a walk-off shot in the 10th. The next day the Yankees were losing Game 5 when Scott Brosius tied the game with a homer, and the Yankees won in the 12th. The Yankees, just 6 weeks after September 11, were destined to win a victory. Not just a victory for New York . . . but a victory for America.
Luckily, good pitching trumps jingoism. The D-Backs said "F*** momentum" by winning Game 6 in a lopsided victory, then came back to Win Game 7. The Yankees had the momentum, but it didn't get them anywhere. And every reporter was writing about how the Diamondbacks were finished after Game 5. And none of them were brave enough to write a column after the Series and say, "Everything I said about momentum was a big ol' crock of poop. I'm incredibly stupid."
Think these are the only examples? Read the Gunn article to find out about similar stories in the 1999 NLCS, the 1975 World Series (Fisk hit the homer, but the Red Sox still lost), the 1972 ALCS, the 1947 World Series, and the 1911 World Series.
Momentum is bunk.