The matchmaker needs retooled for role queue. It clearly matches by average TEAM MMR, and it needs to match by average ROLE MMR. A team-wide average was sufficient for open queue games where switches could happen, but is completely inadequate for a role-locked match.
Platinum tanks fighting Silver tanks will never be a fair fight, etc. If your team has a DPS SR average of 2500, the opposing team should have DPS with an average of 2500 SR. This doesn’t happen and is trivial to verify.