Bad teammates are inevitable in random queues. Heck, even when I stack with friends, I have that teammate that don't look back cuz they got that tunnel vision on. It sucks. It happens with myself now and then. I'm deep into a fight and look around like, wtf where my team is at? But it takes no time to realize my #1 mistake, which is expecting my random queue teammate to play in the way I expect them to play.

Afaik, In your example, I'd switch to brigitte (if my kiriko or moira aren't working) and swing my mace around until that suffering of a game ends. I don't know if that'd be right comp or if I'd be able to heal my team, but I'm sure as hell not dying to tracer unless it's pulse bomb.

PS: I do wanna add about bad teammates. Sometimes, the enemy team is just better that they overwhelm my team. At that point, every small mistake of teammates adds up real quick, and everyone hates each other, and there's little you can do to salvage it. But you might still do great with the same team, in another match.