solo queue balance and MMR

can some one please tell me how the solo queue matchmaking is set up and how MMR works? I was once again placed in a game where the highest ranked player on my team was a silver 2 and the enemy team was sporting a gold 5, a diamond 5 and a platinum 2. please I'd like to know how the balancing works if there is any at all?! It seems to be a trend in my games I am offten placed up against players of much higher ranks then I or my teammates.