In baseball, winning in October isn't quite the same task as winning in April through September. It's not some abstract will to win or aura or mystique or anything of that nature, but the simple reality that winning in a short series requires different planning than winning over 162 games. Your stars don't get normal days off, situational players such as pinch runners become more employable, and the front of your rotation and bullpen play a more prominent role.
When it comes to lineups, your choices are more situational than over the long haul. Each game is vastly more important than games played over the long grind, and far more scrutiny is given to individual matchups.