Possible glitch in the ranked system

I have just finished my promo's and have won 7 games. I have lost 3 games; 2 due to troll/afk/feed. I have been promoted to bronze 4. What I dont understand is that last season I was almost Silver 5/bronze 1-2. This season, I go straight into bronze 5? It doesnt make sense. Season 2 I was silver 4 which was my first season playing in ranked games. I had won 7 games and lost 3. This season I get promoted to bronze 4? really? According to this logic, If I had won every single game; I would of been bronze 2-3 at most not even bronze 1. So WTF is this bullsh1t. Someone please explain.

Thank you.