Honestly MMR doesn't care about win rates when it builds a match, Your losing a lot? You fuck your team more games then not? YOU go down. You do this next game? DOWN! repeate until you stop being a handicap. Same thing for winning a lot. Win? gain MMR. rinse repeat.
It wont care. its all RNG. It works when the MM uses a fair range to make matches. It works with a fair K factor on uncertain accounts.
MMR is off wins, losses, draws. The quality of a match, how often you see pleasant or toxic teammates? That's entirely off player population and behavior. its going to try to make a game that's "50%" by grabbing 5 players in the range it considers fair. Then grabs 5 other players from its range that's fair. then put them in a game. The teams MMR is added up and averaged to be near the other teams average.
The range for Fair basically is to not have a player whos good games are literally unwinnable vs another players off games.
Also who the hell is insta downvoting threads? some one got a few bots or a surplus of extra accounts? Its garbage to bury conversations you disagree with or don't want to become visible and its suspicions as all hell this has been going on for the last few days where a new thread instantly gets 15-18 instant downvotes with 0 comments when the OP is not shitposting and actually has some content.