Promotion matchmaking

I am a bronze player, although my MMR says its normal for my league placement. I am currently struggling to go from B2 to B1, as a support. Every normal ranked game, i am put into a normal team (very balanced). Every time i go to promo games, i am put in really dissfunctional teams, like the system is against me. 1st promo the mid was like 2/12/3, and the jg like 2/13/3, plus the top was afk. 2nd game i had the worst ever jinx (she didnt even know how to farm), plus the mid and jg were like 4/8/2 and 4/8/0. This happends on every promo game. It's really annoying and i think i will go back again to HotS (by the way the new mini quests in BLITZ are inspired from there: Hanamura, Cursed Hollow, Drago Shire), where the promotion mechanics work really well. The matchmaking system is just like it doesn't want me to promote.