I was doing some futzing around, and I found a nice little study that showed why the A's couldn't get over the hump early this decade:
ESPN.com: Page 2 : Why don't the A's win in October?
The main point is that they identified three major factors that correlate strongly with postseason success: quality of the closer, strikeout rate of the pitcher, and defense.
And, if you think about it, it makes sense. The difference in talent between playoff teams is so small, most of the games are likely to be close. Thus, the quality of the closer makes a big difference.
The strikeout rate and defense are also important because those are how you keep runners off-base. Offenses in the playoffs are generally very good and efficient, so you want to keep people off the basepaths.
So yes, pitching/defense wins championships. This might also explain the struggles of the Yankees in recent years, where there offense has still been great, but the defense has been poor and the pitching has been suspect (although the closeris still awesome).
They also found that the 2000 A's were one of the worst playoff teams of the last 30 or so years based on a combination of those 3 factors, which makes sense that they lost in the first round. And, considering the team didnt change THAT much in the next few years, the 2001-2003 A's were probably near the bottom too.
*EDIT* The reason why I put the post in this thread is to show evidence that it's not a TOTAL crapshoot (which I never really believed) and that there are certain characteristics that are common to most successful MLB playoff teams