Lost rank and banned even though I reconnected and won?

[wienermerchant42]

My internet quickly cut during my game, probably spent 5 minutes disconnected out of a 40-50 minute game, then reconnected, won the game, and still had 75% kill participation for our teams kill spread and I receive a ban and loss of elo? Why?

I understand punishing leavers or straight up disconnects but I reconnected shortly after and won the game.