just a short explaination for the players which ask "why is player xy so powerful in PVP, how does he perform so well"
basically the power comes from the things that award gearscore: gear (up to 115% + dragonrelics-gear + relics up to level 10)
everyone who would have these things would perform exceptionally, no matter what class he would play - thats why we sometimes see players doing really well although they play a non-favorable class
so their true performance is not so much the act in the battleground but the acquiring of the highend-gear they have
being able to kill everyone in BG with ease is rather the "reward" for all the effort they took to get their high gearscore than a performance on its own