I’ve been playing Halo 5 now for a couple of years and the ranking algorithm needs to be greatly simplified IMHO. For example, in Arena Slayer I can score 3 kills 20 deaths and if my team somehow manages to win, my CSR goes up. On the opposite side, if the top player of the losing team scores 20 kills and 3 deaths but still loses, he loses CSR points. This just isn’t a fair way to achieve a true CSR rank in my opinion. I have ranked up when I played horribly, and ranked down when I played terrifically. I’m currently a Plat 3 in Slayer, and it’s the norm to get totally mismatched teams, not by their CSR, but by their skill level. I’ve played against Gold players that’s should be Diamond or higher, and conversely Onyx players that should be Gold. This makes for extremely frustrating gameplay as you never know what actual skill level you are going to be matched against. It seems to be either extremely easy to win, or impossibly hard, with very few evenly matched teams competing.
My suggestion is as follows. After the game is complete, simply rank all 8 players from highest KDA (or KD) to lowest, irrespective of what team they were on. Then give the top player the most CSR points, the 2nd place player less CSR points, etc. The top 3 players should obviously gain points, and the bottom 3 players should lose points. Perhaps the 4th and 5th place players should have no points gained or lost. But that way, an individual is always very close to his/her true skill level CSR, and then the match-making would be more fair for both sides.
I welcome any feedback.