MMR and CSR Doesn't Work

For my this Rank System don’t Work. I play many games that last a long time because the two teams have the same skills. In the end when I win I earn very few CSR points (+ 1 / + 2, + 5 / + 6)
There are other games in which the enemy team destroys us although I have a positive K / D ratio (Maybe because they play as a team) and I lose -15 / -10 CSR.
This is unfair.
Overall I have a lot more games won than lost, which means the system doesn’t work, and my MMR is extremely wrong!
Do you also encounter the same problem?