I feel you, I honestly do. Ranked game is always like "OK, everyone tells me that I should climb easily if I don't really belong in this elo. So I have to single-handedly carry my games to victory. To do that, I will only play champion X in role X and from there I'll be able to snowball the game."
Compared to the normal games where I already play with people I feel are like me and I can experience huge fuck-ups from my side and genuinely learn from mistakes. I had a game this week where I fucked up the last teamfight. I was mispositioned in the fight and died almost immediately. There was nobody else to blame. It was all me. I lost the game. This was so eye-opening and I was lucky my teammates were decent people so they didn't flame.
This won't happen in ranked. At least not for me. In ranked you only try to baby your teammates through the game, make sure they survive the laning phase mentally and KDA-wise. But you can't test your own limits and your own weak points because it's just not challenging.