When you take part in a tournament the points won during a game will determine your position in the leaderboard.
The leaderboard isn’t final until the tournament has ended.
Can I appear several times in the leaderboard?
Yes. During some tournaments, you can get several Rebuys. These allow you to start a new game and therefore appear on the leaderboard several times. To know how many Rebuys you can get, check the tournament’s General tab.