They say that we won't lose certain ranks, no matter how many times we lose. I was Silver 1, and when I opened the game after an update, I was back to Rookie 1! And I was Gold 1 and they did the same sh*t! I am Silver 1 again! I had
to win a lot of duels to go up and it happened again
At the end of a season (end of a month) all players will be deranked by 5. King of Games to Platinum 4, Legend 3 to Platinum 3 and so on. However, you won't be deranked below Silver 1. In the past, Konami made 3 mistakes not following this rule: Once they deranked all players by 10, twice some players got deranked below Silver 1 (both were issues connected to the World Championship and Kaiba Cup, triggered only if you played a ranked duel before WC/KC first or vice versa). All 3 mistakes were unintended and explained by Konami in the in-game box.
They reset the ranks every month, so everybody goes to the same position, but one rank lower. If you went from Silver to Rookie instead of Bronze, though, you should report. It's a mistake.
you wont drop from them by losing however rank reset happens at the end of each 'season' (start of a new month) and you go down by 5 ranks every time.