Match making on quick match

I queued as Zarya, Blaze and Brightwing with my friends and we got two bruisers on our team each game. When I play ranged assassins I get match up with other ranged assassins. I’m not sure what is causing this, especially since one game we were matched up against three assassins. It would have made more sense for one of those assassins to be on our team and one of the bruisers to be on their team. I’m not sure if this is a bug or matchmaking having a lot of issues.

QM randomness, MM just wants to give you a quick matchup with roughly even MMR on both sides.

The latter. As far as I know is that only tank and healer are “mirrored”, the rest is just whatever QM gives you. Sometimes this unfortunately results in such uneven matchups.