Actually we can't know what it is for a bunch of reasons. A better way to look at it is to think of some people as KD generators (they die a lot) and KD consumers (they kill a lot). A lot of KD generators aka scrubs don't play anymore, removing them from the population and pushing avg KD up. They still exist in stats from the start of Destiny but have no relevance to modern crucible. We're probably talking millions of people here btw so the effect is large. Another reason is that mean and median are not the same but i don't expect you to understand that.