Solo v Premade

It's a totally different game to play as a solo vs playing as a pre-made. I understand why Riot needs to have both solos and premades in the same queue. If Riot didn't put solos and premades in the same queue then queue times for premades would be unbearably long (imagine having to wait for a 3 man premade and a 2 man premade of equivalent mmr with the right role matchups to make a team of 5). However, it's fanciful to pretend that it's the same game or the same skill for solos and premades.

The games though are so different. As a solo, it's really hard to execute a good dive or to juggle aggro. If you are on skype with your mates, though, it's way more doable. Same with objectives, if you want to take baron or invade or do a risky dragon, it's way easier if everyone is on voice comms to respond. Solo players that play at the higher levels essentially have to be doing other things better to play at that level.

So, make separate ranking / mmr. If you play solo, you should have solo mmr / solo ranking and if you play premade, you should have premade mmr and premade ranking. Just like old 5 v 5s.