Yup, fair play. By nature, any skill measure could be influenced by the player...so my view would be to add this as an increment improvement without telling players.

That could work. Of course there is the aspect that now the best players of the worst tier will go flawless. I dislike that idea. Why? Because the worst players of the best tier will never go flawless. But it depends on how they structure it. If each tier had a small window of k/ds, then it could work.