I know that HLX is supposed to run proportionally on kills. For instance, and these numbers are completely made up, if you have 500 points and you kill Fearless with his 2,000 points you get 8 points for killing him and he loses 8. But if he killed you, because he has four times as many points as you it's expected he'll kill you a lot before you kill him so he only gains 2 (the minimum) and you only lose 2 when he kills you.
You also get bonus points for large kill streaks without dying. So even though you think he would have to kill you four times without dieing in order to just even out, it would only have be 3. He gets 6 points for the three times he kills you and 2 (kill streak of 3 minus 1 point) for the killing streak.
It's set up this way so that your skill level doesn't keep rising simply because you play a lot or have played for a long time. It will represent an actual skill level more accurately. For instance, according to GameTracker I'm one of the highest ranked players on FF Off but I am not that great. The only reason my rank there is so high is because I've played more than twice as much as the next highest time on the server. So even though I'm almost tied with the person above me he's had the same amount of points in half the time.