You become "better" at PKing the same way you get good at 1v1-- hit other people more than they hit you, and have a higher KD ratio-- metrics the game does not even measure. The only metric the game does measure is kill count, which only shows the amount of time you spend on the game x your "efficiency." And the "most efficient" way of adding kills is braindead button mashing in a highly dense spot; at which point can hardly be called a game anymore, so what's the point?