Read VKC’s post here: PvP Pairing System Fraud (The Neogate) - #87 by Dev_VKC
Ultimately, you get matched based on how successful you are. If you win lots you’ll advance higher and face tougher people. If you purposefully lose lots there’s a limit to how far down you can go, to stop it from being exploited for easy wins during ranked PvP. When you’re low hero rank I believe the game will not push you out of the beginner tier unless you get a high win rate. Previously it would keep you there even when you were winning lots but they changed that to stop exploitation.