Fix your mm

So, I'm playing ranked and I'm getting decent and fair teams there and there. I get in my promos, and every SINGLE person has an mmr of bronze 5, plays like a bronze 5, and acts like a bronze 5. I had a top lane AND jungler going 0/12 laning phase like 8 minutes in. Bot lane going around 2/12. And I'm mid lane going 8/2 at first. Then, they fed their asses off even more and we lost. NEXT game in my promos, my team does the EXACT same thing. Play like new players, and feed their asses off. Why is it that it only happens when I'm in promos and not anywhere else?