I know that feeling.... as in I gave up..... bought a new game to play instead (I'll be back in preseason).
I'll probably never play ranked agian.. aleast not for another year, that was a terrible experience.
The champion I am really good at... is Nami, I played as many games of her as I could... I lost almost all of them. Supports have no control over how the game goes. It all depends if your ADC is good and your solo lanes don't feed. None of which I had for weeks.
i know how to do so many game concepts, that my allies and opponents don't.... I have played the game for 6 years...I commited myself to winning games of ranked and I lost them, all of my efforts were worthless, It wasn't even what my final rank was it was just that I put effort in and I wanted results out, I got the opposite results and so I quit.
Ranked is not worth playing.