Also if you're doubting the mmr system.
I was in silver 2 before the ranked reset, and after a bad promo series was put back in silver 5. I was pretty annoyed since I had worked to get from s5->s2 through the preseason and figured I'd have to climb again.
I was back in silver 2 in about a week. The skill disparity even between silver 5 and silver 2 was massive. I consistently went 5-0 or 10-1 or 8-3 until my mmr was back where it was supposed to be, and it was just effortless climbing back. People warded less, didn't control dragon as well, had poor mechanics etc.
Basically if you aren't where you belong, the system will work it out very quickly. And if you're where you're belong, it might seem frustrating, but you won't move very fast at all.