Well I've noticed a slight bug with the auto-aim feature available for controller users. Sometimes the auto-aim will randomly lock onto your own character which then allows anyone near you to be able to hit you perfectly even when they are shooting in a completely different direction. I had teammates kill me when they weren't even shooting at me or near me when the lock on icon was showing up on my character.
The only fix I've found: Use a mouse and keyboard when in /deathmatch.