Sometimes I disconnect from the server, this happens randomly not just in arenas because internet in my country is pretty...unstable, and that makes me lose quite a few games.
That once happened when I was YOLO trying to 1v2, and when I was about to lose I got this disconnect, when I could finally reconnect people said that I was abusing this.
This sometimes happens with people that use free VPNs too.
So, in other words, if they are going to formally implement a rule or something like that(regarding ban, while they can't fix it), they should make a mechanism to identify when it was a legit disconnect and when not.
The easiest way, of course, is just fixing the bug, making people lose rate(flagging leaving battlegrounds as a loss, thus also granting rate for the other team).