Position dependent ranked is just baffling to me.
From what i read, the point of this change was to reward players who play multiple roles and give them a way to feel good/better about it.
As a person myself who plays all roles, but mains Mid and support, this sounded great to me. Its been documented time and time again that one-tricking makes you climb faster, and i personally think that is a problem because it actually shows a flaw in the system if limiting your scope of the game actually gets you higher in ranked.
But that is besides the point.
This change, ironically enough, does the exact opposite of what Riot wants it to do.
By separating each position into different ranks, you are punishing people for playing more than one role, and further encouraging them to just play one. If I know my games playing ADC don't count towards the ones where I play Mid, then why would I ever play ADC?
This system actually DISCOURAGES you from playing more than one role, since the time you spend in each role don't accumulate with eachother but instead are spread thin amongst one another.
Additionally, how does this system accommodate for lane swaps? Either it detects based on your champion (which would be asinine.) or it doesn't leading to tons of trolling/abuse cases in queue.
It just all around sound like a bad idea, and it boggles my mind how little this was thought through.
Unless you get some kind of secret overall Rank from the accumulation of all your ranks, (which would be hella abusable) i don't see how this accomplishes what Riot thinks it's supposed to.