Not to mention there is a pet bug in 2.3 which has to do with the way pets (locks and hunters) behave. Pets try to get behind mobs nowadays, so they can miss the attacks of a cleaving mob/boss.

Imagine the mob turned wrong, or a polygone in the way or something, the pet will be disfunctional enough to walk the entire instance to get behind it. Trust me, I have had it happen before (no more lazy killings on mobs, need to pay attention or I will whipe a raid ).