Ranked bugged in Season 4?

Last season (3) i finished plat 4. But now (season 4) I got placed at diamond 2 and after winning 5 games ( and loosing 2) i got ranked up from diamond 2 to masters 4. Is this a Bug?

edit : i barely played ranked in ow 2 i just did my placements maybe twice

I was silver 4, and after the update I was bronze 1. Something funny, 'cause I don’t deserve a bronze, neither silver… neither gold. I just uninstalled the game watching diammond known players who are clearly worse than me