I can confirm this. I hadn't played much ranked for a while before starting out in this season and my first 10 games were abysmal. After that, I finally got everything together and figured out again how to be useful, so now I'm sitting at a basically 50% winrate on 1100 rating, never dropping, but never climbing either, after about 300 matches.
Then I made another character of the same exact class, with the same exact utilities and everything, and passed the gear onto it, and made it to bronze after around 40 matches. That character is also sitting at a 50% winrate now, but in bronze, at around 1230.
I think, those very first matches you do on a character matter way too much.