The best team in baseball only wins about 60% of the time. If they play a tema who's only won 55% of their games, they may have finished 8 games ahead of them in the standings, but their chance of winning any series is likely no better than 55%.
That's baseball, get in the playoffs and you have a chance to win.
The last two times the Cards have won the world series they were not the best team. That's not to say they didn't deserve to win, because they did win. But the best team frequently loses a baseball game. Otherwise there would be some teams that win 140 games in a season. But the randomness of baseball ensures inferior teams win all the time.