Sometimes I’m constantly getting high impact kills and helping to win games, sometime I play horseshit and cant seem to even get 10+ kills. Is there a way to improve and become more consistent with my plays?

In my last game I had a Sage in my Team, who would only heal her mate (Raze) and herself. We lost 13-0 and I wondered myself why people would so this. Like what is the benefit of healing urself on 80 HP instead of the 3 HP phoenix? And she...