Ranking system

I liked the idea of this system at first, I placed diamond after going 9-1 in both slayer and arena. I grinded my way up to onyx, but now that I am in onyx I realize how crap this system actually is. I have never joined a solo game and played against other onyx players, usually plat or gold. How does this work? I want to get my rank up but i I have multiple pictures of me winning these games and de-ranking because the game matched me against low ranked opponents. How could I get punished or drop csr because of this?? Screenshot - 3d0f7142cdb8db2c934f4f4e29e20c41 - Gyazo

Happened to me once more today, this needs to be fixed.

I don’t understand this either…

Sometimes I have a 3.5 kda and get ranked down… Sometimes I play like stupid with a KDA of 0.5 and get ranked up… I don’t understand this ranking system at all.