Understanding Ranking In

Help me understand ranking in. I used to rank in around Plat 2 and then end the season at Diamond 2. That’s how I thought it was suppose to be. You would rank in multiple levels under where you were suppose to be. The last couple of resets I would rank in at Plat 6, just below Diamond one and then by the end of the season be at Diamond 2 or 3. Am I missing something? Please explain. Tanks.