The AI are a major part of this game in both single and multiplayer so when there is a problem with them there is a large impact on the game.
getting to the point, the AI have several issues during combat including situational awareness, reaction time, detection of other players/AI, unaffected by recoil (especially machine gunners), ability to see through solid objects, unaffected by suppressive fire, a bullet wound is nothing but a scratch to the AI, unbelievable accuracy and probably much more.
Situational awareness: whether you are behind cover or hidden by concealment or even stalking AI in the night. They always and i mean always know were you are so therefor all the above mentioned aspects are obsolete when used against AI.
Reaction time: If you are behind the enemy, far away from the enemy or concealed by a bush. The AI (once they have detected you) will start firing directly at you within around 0.5-3 seconds no matter how far away you are.
Detection of other players/AI: the AI have seem to have super senses because they can see you at ranges of 1km under the above mentioned reaction time (provided you have fire your weapon) even if you are concealed or 85% of you is behind cover and this is a HUGE problem if you are trying ambush the enemy. they can also see you under water (AT NIGHT)
Unaffected by recoil/Accuracy: the AI seem to keep their gun aimed at the same point (almost exactly in the same place) firing on fully auto at ranges up to 200m (machine gunners have this accuracy at 800-1000m).
Ability to see through solid objects: AI have a huge advantage here as they can fire through tree leaves, closed windows, tall grass, bushes and anything of that nature and this eliminated concealment when you are against AI (this connects the there detection and reaction time as they seem to detect you (after firing one shot), locate you in 0.5-3 seconds (range is ignored) and then fire with unreal accuracy).
unaffected by suppressive fire: The AI are only affected by suppression a little (fair enough it can work from time to time) but despite the little effect it has the AI is still always fire at you (just maybe a little less accurate).
unrealistic reactions to bullet wounds: I highly doubt that if you get shot in the knee, arm, leg, hand, foot, gut, chest and on rare occasions even neck and head that you would just say "oh no worries i have just been shot in the gut!!" and continues fire like he if all good and healthy. i think that there should be at the very least a 10-20 second wait (even applies to player) before able to function again.
so all this all adds up to an unfair fight for the player because you are a human and the AI is a superhuman. I mean sure they have their defects E.g. running out into the open, not using houses but if they did have these defects fixed they would only be harder to beat so just a word of warning if there is going to be a fix for the defects please fix the above list of problems first as it will at least give the player a chance to get a better experience out of single player (and sometimes multiplayer).