So, as I wrote in some comments today, I figured out why dmg done and taken don't add up. After I played instagib in the morning I noticed that the dmg numbers from the match I played look really weird. For 50 frags you will deliver 33300 damage which is 666 per frag (opponents cannot have more then 125 hp), and for 9 deaths I recieved 1041 damage which is 115.667 per death. This made it very clear to me that damage dealth is calculated from the shots you fire rather then from the damage that your opponent recieved.

In my opinion this makes the numbers really useless, since it will clearly favor rocket players, and maybe rail in some cases. It would be really bad for lg players since they would only get pretty much exacly as much dmgD as the opponent has taken.