Bronze player in platinium elo ?

This guy chengbijie6 was my adc, they were 5 plats and we were 4 plats + 1 bronze. The bronze player had really hard time managing to poke, trade, or even set good traps positions as cait. He didnt had a minimap map awareness so pings didnt helped him even when we had wards at the map. He couldnt farm either. Someone from my team said that this ACC is boosted which can be the case but I noticed that i have really hard games lately, i dont know if its me the problem but i started to lose more than i win which happens very rare. Are there any ranked changes that i am not aware of ?