There are hidden tiers where players can only go up.
Imagine there are 6 leagues, rookie, advanced, elite, expert, master and champion. Players in the rookie league only fight other rookies when PvP starts. Good players advance to the next league.
Which means, if you were original master league player and have advanced to champion league, by losing battles on purpose, you can only go down to your placed league (master league).
There are also hidden ratings determining who you will match within the league.
We will reset these “leagues” when 2nd half of PvP starts anyway, so it won’t matter that much.
I hope this explains your concern.