Quality Matchmaking Balance

Normal MMR is separate from ranked MMR.

This is because people play ranked to win, but may well play normal games to learn new champions and are definitely not playing at the same level.

Alternately, there could be a duo-queue in there somewhere screwing things up. I've previously played with plat/diamond party members, and I'm kind of terrible, myself.

Normal games bro... have nothing to do with Ranked status.