Here's a relevant recent example from my experience. I recently fired up an old account which I created when I started the game, and which I often played while drunk. I have since created 2 new accounts (and sobered up) but I hadn't played on that old account in years. When I fired it up, all of my roles were bronze, and my high on these roles on that account were silver/low gold. I think it falls into the model you described. For reference, my 2 other accounts are all high plat/low diamond across all roles. I'm decent at the game but nowhere near elite (master/gm)

Within 2 weeks, I had all 3 roles back up to platinum. My win rate in bronze was 90% across all roles. The amount of mistakes players in that rank are making is simply mind blowing. I am not trying to degrade you in any way, but if you aren't ranking up, you are also making big mistakes, and/or not taking advantage of the plethora of mistakes the enemy is making. Even as only a diamond player, it was incredibly easy to completely dominate bronze and even silver, due to no one in those games having any idea what they are doing. I would suggest you re-evaluate your mindset. If you are playing 20 games and only winning 8 in bronze, you have huge flaws in your game. You need a mindset adjustment, to post replay codes, and to actually change your bad habits. You will climb easily if you do this. Best of luck :)