ELO - How does it work?


So, I’ve been playing FaceIt for a little while now and I can’t seem to understand the ELO system on CS at all. I have some examples to back this.

Example 1: We’re smashing a team 15-3, they haven’t had a leaver, they surrender in the final round. We only get 12 ELO. Cool, great reward for demolishing a team and making them surrender.

Example 2: Played a game where we had a leaver in round 9, as a 4 we managed to take it to overtime then lost when we technically had the ‘worse’ team. We lose 30 ELO.

With both examples in mind and as a comparison, how is this even fair and how is it calculated? I’m interested to know what kind of formula there is behind it. If there is any, because it just seems absolutely stupid.