I hope next season you'll look at last season's MMR for matching.
I just got out of a game where I had a D5 ADC in a low gold ELO game. Needless to say... they carried and went 19/4 (but really, that was just 'cause of my Challenger level support skills, yep, totally).
But really, that shouldn't happen. So, next season, make the matching at least a little bit fair. >.>