Ranked Slayer CSR Craziness

So I have been playing for awhile and I would like to know why when a teammate quits out and your team loses why you still lose csr even if you go positive kda. This keeps happening to me and I am royally pissed. I will lose a 4v1 and still be the only one to lose csr even though I went positive and didn’t quit. I would be fine if that was the new thing but I one time beat a team with onyx who went negative, had a full team, and my teammate left. He gained csr even though he wasn’t the leader of his team and went negative in kda. I gained barely any csr. This is ridiculous I don’t know how because I was the highest on my team at platinum 5. I really would like to know what you all did to the csr system that screwed it up so bad.

You need to check out the matchmaking feedback and FAQ threads, all of your concerns are addressed there.

The Halo 5 ranking system is based on ranking the players based on performance compared to other players and use that ranking to find the best possible match for everyone. This system is based on a mathematical model called “TrueSkill2” and the CSR level is designed to converge towards that ranking but at a relatively slow pace. If you perform poorer than the game expected, you will lose CSR and if you perform better than expected, you will gain CSR.

If you wish to get a deeper insight about how the ranking system is designed, then I would recommend to read the papper TrueSkill 2: An improved Bayesian skill rating system which is authored by Minka T., Cleven R., Zaykov Y. (Microsoft, 2018).