Win/Loss. Super frustrating to go in alone and try to rank up.
It's better than the individual CSR method. It only takes into account the final "score" tallied by each individual. You can go 15-0, your team wins, but if you're not listed in the top 1/2 of all players in the game according to score you still get a "loss" added to your CSR.
I guess the only way to rank up is to play stupid and rush rush rush all the time. Who comes up with this?