Its kind of a myth, kind of not. Ideally the mm would tend towards 50% win rate. The issue is how it gets there. If it could make close games that were 50% chance it would be one thing. What happens is they try and average mmr. Lets say your team mmr average is 2k. It will try to make the other teams mmr 2k. If it say takes 3 2k players 1 1500 mmr and one 2500 mmr player to do that iy can be ok the prob is it will give you 3 2k players 1 1k player and one 3k player. Which is bad for both sides. I had a ranked game today only last 9 mins 13-2 every one was diamond 1 or 2… they had the better team comp, but they also had 3 feeders. 2 had 4 deaths at 5 mins. The other had 4 deaths at 7 mins. That was not a fun game nor was it fair for the 2 other players on thier team that playes well