Enemy that shoot your mates to the back usually kills all the squad because only 1% of players sad like "am killed, look around".
It could be extracted from Cnc Tiberian Dawn redux with 1 hour of work.
Battlefield plays that sound only if teammate killed on long distance from you. Usually you can hear it on deathmatch start where nobody started shooting but sniper killed someone with insta-hit.
But damaged teammates or even supressed teammates says always unique talks that gives you operation sitrep. Even if you selected some bonus to "prevent supression" your actor will remove supression effect as a real bonus and as an answer that he say.
How much depth of copying the idea - decide your own way. The idea is via some way notify your player that he's flanked, but in same time dont show the enemy, making spawning inside hard battle less useless.