how does the game calculate how much rating to give/take after win/loss? wtf is this

Was oracle 6, played and won 1 game as drifter, best in almost every category and not even a key player somehow. Rating didn't change, still oracle 6.

https://preview.redd.it/r8zkhc7rwxig1.png?width=2223&format=png&auto=webp&s=05eb48a207f24fe0248373627e783f3f79907d7f

Then played another 1 game as mo&krill, tried as hard as i could but lowkey had like 5 dynamo ults in my solo face in a row, still almost 2x damage of every teamate on fucking mo&krill, and then my rank goes from oracle 6 to oracle 5.

https://preview.redd.it/f0cdllu7xxig1.png?width=998&format=png&auto=webp&s=b2149219f4c080592f633ddadffbf182dd678763

So what the actual fuck is this, i could understand that if i completely threw the game and had lowest damage and everything else, but why i almost solo carry 2 games and loss changes my rank so much stronger than victory? do i have to win 3 games to counter 1 loss?