There isn't any sort of bot AI coded anywhere to handle crowd control.
Bots aren't even really aware of the NPCs surrounding them, regardless of the threat level to the owner. Thus, they take no action at all unless the owner engages first, they are hit by an NPC's AoE effect, or they are implicitly ordered by the owner to take action against a specific target.
I'd personally love to see some more in-depth decision making capabilities for quite a few classes, honestly. Paladins and Rangers who cast heals when there is a capable priest class in the party seems like a waste. Things such as intelligent target changing (for things like off-tanking or emergency peeling of NPCs off INT casters, for example) would be nice as well.
That being said, mucking about with placement would likely much less complex of a task.
