You want to fix zergs and eliminate the debuff?
First remove alliances, may even want to reduce guild sizes. The game at this time just can't handle that many people.
Second, remove all guilds tags and character names in the black and mist zones. Basically all identifiable marks besides health and mana bars (From people not in your guild) and let the true disarray begin. Some people may try to organize several groups but friendly fire will be awesome. Handholding in the dark will lead to a lot of people being punched in the face.
Please do this.