Aim Assist Disabled -- Still assisting?

This has been a nagging issue for me. I have the aim assist disabled so the aiming doesn't pull or help me try an aim at all. I am finding there are 2 players close each other while zoomed in and 1 character runs behind the other, while I am aiming towards the lead character(say he is standing still) it pulls my aim to the runner. I also noticed this in arcade mode with it disabled it does a noticeable "pull".

If I aim straight shouldn't it just stay straight unless I move it? or is this built in and aim assist is something different?