Quote from paendamonium >> My guess is if their MMR system works similar to an Elo system, players who went inactive still maintained the same rating despite the fact that they hadn’t played in some time and the OVR of their time had likely also slipped. That meant if if they return to playing overdrive they would face opponents at a high rating comparable to before the player went inactive, which would probably be unfair.

TLDR: The more overdrive you play and the more information the rating system has on you, the more accurate the matchmaking should be.

 Pretty accurate.