This is how it works. Lower your winrate, RNG is more forgiving and gives you the right cards at the right time. Win lots of games and RNG goes from neutral to penalizing you while doing reverse to your opponent depending on his win rate. If your MMR rate is 60% and your chance of getting the right card to counter opponents hand would be at 40% each turn, same goes for your RNG cards. While your opponent win rate is at lets say 40%, he gets higher chance of getting right cards around 60%. Right cards means washing your opponent at every turn in face value of your working hand. Simple math here. If your win rate goes too high. You get opponents with near perfect draws and can pull easy combos while you struggle to get the right draws. As added bonus, MM matches your deck with a hard counter decks so that you reevaluate your deck often. In other terms, buy more packs to get more cards and build new decks to counter the deck which you lost to. It's a vicious cycle of reorganizing decks and Blizzard matching you with exact counter of your deck depending if you won too many games or not. This is a way for Blizzard to balance matches, has nothing to do with skill, it's all giving the illusion of "worthy challenge" since there is no way of gauging skill (there is little to none), it has to match games in a balance of chance between someone who was too lucky, too successful with his deck or too unlucky. This why everything in this game like every other Blizzard game is heavily dependant on servers and little is done on client side. One is security, the other is rigged RNG. This is exactly why there are no stats in this game, Blizzard doesn't want its players to figure out the mechanics of MM and tilting games by controlling RNG. For any professional Esport player, this should have been a red flag from the start.