Just make ban for people that drop or AFK for 2 min
i dont care about people that get disconnect/bugsplat
people with bad internet should not play anyways
ban for 1 month
And that's how you get your community to decline in full.
Leavers are of course annoying, but you can't force someone to stay in a game he thinks is lost. So - You have to follow the players behavior over a period of games, and then give him minus elo or something for that but banning.. maybe after longer occurences.
Systems like in shooters wont work for CoH3