"Fill" is a joke
Please, Riot, can we stop pretending the Dynamic Queue is fully functional and that Fill doesn't mean support?
I've been playing Fill for sometime now and got assigned support 90% of the games.
There are ways to fix this, for instance, make it so if you pick Fill two games in a row you can't get the same role as your previous game, worst case scenario you'd play support 50% of the time.
Or make it so we have the option to "Fill every role, except..."
Or make the Fill option frequency dependent in a way that every role has about 20% chance of being picked.