if its your teammates fault and not yours, then since they are playing with someone better than they normally do they will go up rating with you.
when i came back last season of mop i didnt link any achievements and just trade chat grinded using only my cr.
you are 1500 cr? pick up a 1500 cr team and if you are good you can get 1600 or 1700.
then you pick up a 1700 cr team and push them to 1800 before they are out of their depth.
then you pick up a 1800 team and go to 1900.
if you play with a couple different teams at a given cr and dont move up then that is where your skill level is at.