Does anybody know what determines the "Skill" value on crysis3s.com website?

Specifically, I'm referring to this portion.

My sub account that I used is somehow ranked 2, but my real account is ranked 22nd.
Looking at the values, it seems that I'm the "top" if to disregard other ridiculous values (I am not boasting, please note).
My friend who is much less skilled with lower rank and a KDR of below 0.8 is ranked 17th.

So, again, my main question is, what is skill and what determines its value?