this game is peer2peer, so its abigous... you think they disconnect (connection broken between u 2), they think you did. It can happen if the link between you becomes broken.
Internet is like a web. there is more than 1 way between 2 points, but one is chosen as best and traffic goes over it. If it stalls on some point (router hanged up or power went off) your traffic could immediately go via another route but that is forbidden for protocol reasons (if you allow it to switch immediately - that would cause some very nasty instability situations hard to explain in one post). So when it stalls, instead of instantly switching it freeses the connection and waits for 1-2 minutes for connection to restore, only then i will change the route.
So, it may happen that when a hangup happens, some of players are on one side of the barricade and others are on the other side. That means, that you see some players disconnected and some still on, and they see your bunch of players disconnected and their players still on. Both your and other party did not loose the connection to the internet, just one of the routers that carry your traffic went down.
The problem is, on wich side the thing that logs wins and loses is. If it stayed with them - you will have a loose, and if it stays with you - you will have a win.