Still nothing on mob positioning bug, eh?

It was pretty bad in 3.3, but then we fixed some things in 3.3.3 to get it back to how it felt earlier. In general, if you don't move at all, then a mob targeting you shouldn't move either. The only exceptions would be if they were trying to coordinate with their own allies in some specialized cases. But if you move, even if you rotate or shift just a little, then the mob is going to try to get back into position as well.

There's some interesting speculation above for reasons I am perceived to have given for why the situation exists. :) The actual reason it exists is that if mobs did not quickly reposition, you could get them into a mode where they couldn't hit you because they would always moving back into position to hit you. They would be doing too much adjusting and not enough hitting. (I'm simplifying a lot, so suggestions like "Why can't they just move and swing at the same time?" aren't super helpful.) We don't want tanks to feel like what they're supposed to do is shift around constantly to minimize taking damage. It's a fine line between mob movement feeling correct and minimizing potential exploits.