Matchmaking balancing seems broken

I regularly get into really unbalanced games in matchmaking, last game I had was 14% and one before that was 57% balanced. How can this be? Its really annoying when you just lose in a teamgame because of this.

The matchmaking should really only allow games above a specific boundary or at least not allow premade teams to break balance. 14% balance is unaccaptable and just a waste of time.