Originally Posted by
Lysah
Well that's the trick the system uses to keep people at 50% =p
If you're at 1800 MMR but 55% wins it's going to assume you're better than 1800 MMR. It could put you in a game full of 2000 MMRs, but that wouldn't be fair to them. So instead, have some other 1800ish players, but to counteract the fact that it think you're better than 1800 because of your winrate, have a free 1400 ally. Introducing the fail train of massively feeding allies. Of course, it turns out he also somehow has 55% wins, so both of you get the loss the system thinks you deserve.
People have complained that the ELO/MMR systems have very little to do with skill at the end of the day. There's a lot of merit to it, and it's horribly frustrating. However, in theory, if you just keep playing and deserve to be high rating, over time, you'll get there. You're still not going to have a good win %, though.