Why do I suck so much at ranked

(Rant about a how i suck)

i consider my self a pretty average player with 400 wins in normal but when i get into ranked it would be better for me to afk then feed so much i mean everyone is like diamond/gold and i'm in the provisional's. I play sup because i cant be trusted to carry for SH** and when i vs a Blitzcrank i can not for the life of me doge him consistently about 70/30 and everyone is wondering how i'm so bad as to be garbed by him. people think I just turned lv 30 when i have been lv 30 for a year now so why am i still so SH** **in ranked everyone dose so much damage i cant do anything and if i FU*K up ONE TIME i'm dead and everyone hates me, they say omg u died to a Vayne, well please tell me HOW DO YOU RUN AWAY FROM HER.

I feel like i'm not vising people my own skill level but people 2X better then me, is the matching bad or is it just me? And i know ranked is relay bad for my health (depression/anger issues) but i want to prove to myself that i'm not a bag of SH** and that i can become better but i just feel that it is impossibly with my skill.

Dose anyone else feel like this or am i truly just a bad player?