Ranked Frustrations

So the new season has started and i was fairly excited. I played my placement games and won 7 out of the 10 required. Thinking i was going to be placed in silver 5 or bronze 1, but surprisingly when i got out of my last match it said Bronze 5. I really honestly dont understand how this works. If i would have won 10 out of 10 would the best i could get be bronze 4? Im pretty aggravated about this considering i was placed in silver 1 last season.