Kd is less a reflection of skill and more of a reflection on the influence you will have on the success of your team. Someone with a positive kd will likely have a positive influence on the teams success because they will be eliminating more enemy targets than dying. This can indicate that someone is just a good overall slayer but does not indicate whether they can hold down a position in control or protect a runner in rift. Essentially the higher the kd, the more likely the person will positively effect the outcome of the game. Another stat to consider is also assists, because someone who has a high kda but not so high kd will still likely have a positive influence in the game.