Give every dc'er a cosmetic they can't take off until a few games are up
Upon dcing for a certain amount of games Give them a white paper hat with the letters "DC" on it that the player can't see but everone else can. It would be the default head of whatever charecter their playing and would go away after about 10 games of not dcing.
This would be similar to gtas system actually where they give bad players a dunce cap. Only difference is GTA splits there player base so only naughty players can play together, whereas that would be too big a split for dbd