Recently I've run into several situations on the PS4 where I'll trade shots with opponents and die, and when the kill cam comes up, it clearly displays them as having 0 health, yet they run off and keep playing. I had this happen four times in a single match, each against different opponents that all had the same clan tag, who also subsequently ended up at the top of the boards at the end of the match, so I'm wondering if it isn't some sort of hack...

With BF4 who really knows?

This is a bug. I've been getting it a lot recently too. I had a friend on the other team who killed me and the game said they had 0 health, but when I asked him he said he had 23.

it's a bug that has existed since Badcompany 2.

It's a bug on all platforms that they have said they will address.