I'm not sure placements are very accurate. Gold Solo/Duo, placed Bronze IV in Flex...
Because I'm Gold 4 and am scared of getting demoted before the season ended, I decided to try Flex. For some reason, I did my promos in Iron and eventually played in Bronze. I can't remember but I think my promos were 8-2 or something like that. Even gaining 50-70 LP per win, there's no way I could have placed anywhere other than Bronze.
My suggestion is to use Solo/Duo rank to help inform or weight the Flex placement. Not that I should be Gold 4, but maybe I should be placed in S4 instead of B4?
Unless I try really hard, I can't lose at this rank. It's not fun for me and probably REALLY not fun for the people who have to play against people like me who don't belong at that rank. To make the matches interesting, I'm playing champions I've never played before. Literally no idea what I'm doing and still winning. I'm also doing silly things like suiciding to chase kills because I know I'll be able to win anyway.
Point is, I think it's boring for me. And as someone who has smurfs regularly come and take a dump on me in Gold, I know it's not fun for the enemy team either.
(Side note: I'm getting my first taste of smurfing, and it's so incredibly boring ya'll who do this must be insane)