I'm 60, and killed 1 level 50 mage. And gained (Rank 3, 60%) You don't have to reach 15 HK's to even obtain a rank. This being said, this can put people that are locked behind the potential beta keys which are 200 on/off on a unfair edge if you decide to fix this issue later. I'd say there are maybe 2 ways to fix this.
NOTE: I don't know if there is a cap, but needing only 1 player kill to rank all the way to 3 and almost 4 is a bit weird!
1. Reset everyone's rank to 0. With the ranking fix. And remove their purchased PvP kits.
2. Disable R10 & R14 gears and weapons. For a while.
Open for more solutions!
It's nice sure to have it like this, but it's gonna hurt in the longrun progressive wise and motivation for PVP.