Contribution in QP?

[Yshra]

I did a QP, for instance killed 29/30 mobs in step 1, a random guy killed one in his way.
I did step 2 and step 3 (champion and hero) alone, how the hell can I have only 50 points more contribution?
The roll determines everything, he got 100 more point... So there is no reward for the more you do, just luck?
This happens a lot.