In some ways, managing in the postseason is easier than during the regular season. From April through September, you have to make sure your regulars get days off at the appropriate times, and you can't let your relievers pitch more than three days in a row. Come October, all bets are off in terms of "rest."
Also, since players want to win, they are more likely to check their egos at the door and accept a reduced role in October that they may not be as willing to accept in May, so that helps, too.
Of course, the big difference is that all lineup and tactical decisions receive a lot more scrutiny during the postseason. From where I sit, these are the five biggest dilemmas facing the managers in this year's playoffs.