This matchmaking system makes no sense.
For those of you who don't know how it works, the current system matches you with people who have been doing terribly in ranked if you've been doing well. For example, let's say the average MMR for Bronze 1 is 1200. Player A is bronze 1 but has an mmr of 1400. To "balance" the team out, it'll match you with people who are on 1000 mms, so that the team average mmr remains 1200.
You know what would be a better matchmaking system? If it matched you with OTHER people that are on 1400 MMR. This way you get matched with people that are on the same skill level as you.
Will it make the game more unbalanced? Nope. So then why has riot still not figured it out? Why are they so eager on sticking to a matchmaking system that punishes you for being good?