Most post-season fantasy football leagues are "contest-style" lineups, where you don't maintain a roster, but instead, can start any player once, and only once, throughout the NFL playoffs. The winner of the league is simply the franchise with the most total points after the Super Bowl. So, there's strategy in who you start when. If you think the Patriots will lose in the first week of the playoffs, you could start Brady in the first playoff week. But, if you think they'll make it all of the way to the Super Bowl, you could hold off, and not start him until later in the post-season.