So I've been trying to go through the Co-Op campaign and I'm having a slight problem in Exfiltration and Drop 'Em Like Liquid: They both task you with staying quiet and killing multiple enemies without being spotted and yet those same enemies seem to be omniscent. You crouch and slowly creep up on them to use your knife and they sprout eyes in the back of their heads. You and your partner try a double headshot but one or both seem to have steel plates in their skulls and alert the whole rest of the map in the 1.5 seconds it takes you to put a second round in them. Sniper rifles require 2 headshots to kill unsuspecting enemies and about 5 hits when they're running. And don't even get me started on the "Knife him! *heart attack*" glitch in Night Shift.
It just seems that DICE really put a lot of effort into making the AI smart and perceptive, but went a little overboard.