My conspiracy theory is different. When you are winning a lot during a certain day dont stop. Ive done this mistake several times. "Im like ok it's been a good day, tomorrow i'll continue my climb" but o keep facing counters to my deck and go down.
If u wanna hit legend and u are like rank 3 and above and u are on a roll dont stop until u hit legend. If u leave the rest for the next day u will lose all progress. It has happened to me on the past few days with 2 different accounts. Its probably due to mini pocket metas depending on day of play so my advice is dont stop until u reach legend