So it seems that when you are in a ranked game and your opponent leaves the game you don´t gain any rank points and as far as I´ve seen you also don´t lose points when leaving a game, which like anyone can imgaine, can lead to some people exploiting it. Also it happened to me once or twice now that the opponent didn´t leave a game but I got a meassage afterwards that the host disconnected and then the Success screen didn´t pop up afterwards and again no rank points were given.