you need to be better than all other players that use the same team as you do in particular competition. For example if you choose Real as other 300 players in competition and you have 9 points with +3 goal difference you will probably be around 50-80 in team ranking and wont stand a chance to go through, but if you choose Santos or some other underdog team and manage to win three consecutive games and no one else used that team in competition you will go through top 16 regardless of your goal difference.