The warning only happens if someone dc's after the 1st 30sec of a match so that the people still on the match don't have to waste their time playing an obviously unfair match. Like Ant said, it only doesn't lower your rank if someone else dc'ed first and the warning is still up, but you still get the loss on your record which could still lower your rank.So explain to me why when one teammate leaves, the game says something like. "A teammate has disconnected. Leave in X seconds and you will not be punished." But then you leave and drop a rank anyway? WTF?