Dude it's an ARAM
Not an engineer but i think it's very close to mind to assume that ARAM matchmaking doesn't care about SR ranking
Because normals don't have any correlation to ranked MMR
Your normal games are determined by W/R at the end of your games in normals, if you're like 200 - 100 wins losses you're typically gonna play against real good people but people don't rly care in normals so d1 players can be like 300/300 w/r making it on par with your norms mmr
It's easy to argue normal is not ranked, aram is not ranked. Ranked elo depends on your role etc.
But do you really think so?