Once a player disconnects, they have a 5 minute grace-period to reconnect. If they don't, you win by default. Even though your screen doesn't flash a message that you've won, if you simply click on "Home" or "New Game" you will see that the game is over and the ratings have been affected. At least, that's how it has worked in the 30 min games I've played so far.
Disconnecting on purpose
It pisses me off, too. I just finished 5 games, the three wins were by waiting two minutes after the losing player disconnected. ALL of them!
Perhaps you bring the wrong attitude to it. Just chat: "Oh boy! I'm definatly gonna win now!" to make them think it doesn't bother you. (It's not all that bad either, to watch the clock tick to your certain victory.) And if they log back on to see if you are still there-- which happens pretty often-- your chat message will piss THEM off.
There seems to be more and more players disconnecting when losing. I know players get disconnected every now and then, but come on. When it is obvious... It it is obvious.
I just played a game, five mins into it and the other player is cornered and then disconnection. Then I sit there waiting for the game to time out, after ten mins my computer goes into screen saver mode, I move the mouse and the game is expired. Now there is no record of me even playing it. Weird.
Ok, big deal. But these weeny players know that by disconnecting, their rank will not be affected and it makes the other player sit around all day.
Can any of you say, disrespectful!