I’ve been playing Halo 5 a lot since it’s release on the 27th, and I’ve noticed there’s a lot of people who leave games. Breakout and slayer, especially. In my opinion, if your team loses a game that you had one or more missing players in, the people who actually stayed shouldn’t get their CSR hurt. I’ve been demoted enough times in the already-bad ranking system that paired me up with horrible teams and so for slayer I was put in silver,every other playlist I’m ranked in, I’m at least platinum. Every game I play I perform well above my team, but I can’t carry a game 100% and get 50 kills when my entire team is 2/14 and one of our people left. It bothers me that you can have a teammate leave a game, and get crushed from that point on, and still get demoted, but that’s just my opinion.
TL;DR
In my opinion I don’t think your CSR should go down if you lose a game after a teammate has left. (The winners still go up, and the leaver(s) are penalized, of course)