Autofill question - ranked specifically

Can someone please explain how the autofill system works? I am trying to get a ranked game, have gotten into champ select four times (all mid, my primary role) and someone ELSE has dodged every time. Then the fifth time i get autofilled as sup when I had an guaranteed position I choose before I got autofilled. My question is, does it automatically count as your queued position regardless of whether you or someone else dodges? If so, doesn't that penalize the players that do not dodge? Making them lose their guaranteed role?