They just made some changes. The new system is described here.
Edit: I just looked at your game history. It seems like the first game you played here probably threw the rank calculation way off. You beat a 4k player in your first game, but you’re probably more like ~30k. Now that you’ve come back to the site and started to play some more your rank will get sorted out. You’re either going to have to play more games and expect some losses, or maybe an admin can help reset your rank. I’m not sure what options they have there.