Ranked roles matchmaking is broken, especially in SEA servers. Players pick random heroes into specific roles (For example : Ally picks core for support roles & vice versa in atleast 10/15 matches). Developers least bothered to fix this issue by restricting hero pools based on roles they are playing. Players shouldn't be allowed to play a hero if they have not played a particular hero for atleast 25 unranked/turbo matches. Quality of Ranked matchmaking is way worse than LOL. Can't believe this game has so much positive reviews. If you are facing similar issues, then please change your reviews till they come & fix ranked matchmaking system. Only when the reviews are changed they will be alerted to fix the core in-game issues. I have to say it's a great game but no more fun to play unless you are queuing with 5 known people who are skilled in specific roles. DoTA 2 matchmaking system needs a big fix before this game will reach the worst state from what it is today. It's still my favourite game & I want the game to be better than what it is today. What do you think about DoTA 2 matchmaking?
Source: https://www.reddit.com/r/DotA2/comments/v3wtiu/ranked_roles_matchmaking/