I think the MMR is broken. If you start with an initial MMR 3000. To me, it's almost impossible to get to the next level, i.e.: 4000. Reason? Every game you win or lose will earn or lose you about 25 points. This would mean you need to win 40 games to get to 4000. But it's not that easy, because the higher your MMR, you are supposed to be matched against similar raking players which means the game is supposed to get tougher. So it's fair to say the MMR is designed in a way that the player will usually achieve around 50% win-rate for an average player. With this in mind, it's almost impossible to move to the next level.