Rank system in OV 2 still broken

Hi, i was playing freshly after the new season comp on healers role. I played only 5 games and at the start of this season i was diamond 3 but after i got these 5 wins i got placed in diamond 4. My win rate on support is 100%, i won all the games i played yet i deranked. Please explain how is that possible.
Poof