Today’s update features a change to the rank system that replaces the Core/Support separation with a single rank that uses handicaps for each of the five ranked roles, representing your relative strength playing each position.
Valve said this change will help the matchmaker better account for a player’s different performance levels between various roles. Winning or losing games will modify your single rank.
When queuing for your best role(s), the matchmaker will consider your full MMR. Queuing for your weaker role(s), however, will result in the matchmaker placing you into a match at a lower MMR.
When you match into a game, it will display the adjusted badge levels that were used to match each player. Regardless of which role you queue for and play, the results of the match will affect your actual MMR value.
Your initial levels for each role are calculated based on your previous Core/Support MMR values and analysis of your past 100 games. You can track your current role adjustments in the Role Queue menu.