Off role game tier same as primary role.

I just got autofilled for jungle when my primary role is top and secodnary role is mid. I have never played jungle in this season and it is currently unranked. When I get into the game I saw I am autofilled and I felt it is ok because I thought positional rank would allow me to match with lower elo players; however my team told me that it is actually a master tier game,(my primary role top is D2 and mid is Plat1).I felt really confused because I remember when I played my other role I did not have to play with people that have the same rank as my primary role. I dodged the game because I knew we would 90% lose as I have not played jungle for years. I am just wondering why this happened because this made positional rank seem meaningless.