Also related to the BLU mimicry. When you have tank or healer mimicry the game needs to recognize you as such for the boss' mechanics that target a specific role. For example there are mechanics that specifically target a healer, when you do it as a group of BLUs the targets chosen are random.
I've mentioned this before, but ideally color of your BLU icon in the PF could change to the color of the role you mimic. With red as DPS by default.