Can someone explain to me how is this possible?

@hayhor Based on my badge it should be season 10 badge, that's what I also wrote above that the player had at most 2 split demotions before now and somehow he goes from D4 min to B4...

I only can see that happening if he did not play, then when playing lost it all (went to each splits hardstuck level) and then went inactive or play bad... stuff that usually does not happen with Diamond players...