For some reason when I try to take someone stealthily from behind the guy does a big show of it by kicking the guys leg out then hitting him from behind I want to know how to stealthily takeout the target.
First, make sure you have no lethal weapon armed (It will advise you if you do). If you have one armed, you won't knock them out, but kill them and fail the mission. Second, you need to use the bushes to hide until the moment is right. For each person you want to knockout, the best course of action is to take each target down one at a time. Wait until the target is alone and (from the bushes) whistle until they yellow circle comes up and they walk towards the bush where you are hiding. When they are ready to be knocked out you will see the command "Knockout" next to the Square button at the top (assuming you are using the PS4 version). Push it right away and you will pull the person in and knock them out. You can then move on to the next target, loot the knocked target or finish them off.