There are a number of commands that don't work, and some new commands that turn up. I tried to /mute a player yesterday and ended up with a "nuke" prompt. I killed everyone on the map, and all I could think of was "oops, my bad."
Papa
Yell dosent work with bf4 but it works with bfbc2
No, we don't get a yell either.
So, no way to make a general warning appear on the screen then. I assume that typing warnings in chat will suffice?