The new matchmaking system is proving to be really effective, players are evenly matched, but its a problem with people with boosted ranks and MMRs. The entire player base should be re calibrated, and not with 10 calibration games, the calibration should be extensive, and not just on wins and losses, during the calibration, for a selected role, for example, support calibration, the person's overall support/combat contribution should be looked into, number of assists, deaths, kills, last hits, support gold spent, and every other support gameplay aspect should be looked into while calibrating his or her's MMR.
Same goes with offlaner, mid, or safelaner's calibration as well.
If all of these aspects are looked into, we'll have a very high quality matchmaking experience, which is rare in today's MP gaming scene.
Dota 2 has extensive statistics on every aspect of player's performance, it all can be looked into while calibrating a player. I feel 10 games, are a bit low to get an accurate MMR or rank for the player in any role.

in conclusion:

-the player base should be re-calibrated in accordance to the new update
-the number of calibration games should be 20, to get the most accurate rating
-all statistics of a role should be considered when assessing the performance during calibration, and not just wins/losses

I'd like to thank the devs for finally taking this initiative, Dota is worth playing again, and we'd like to help in making it better.