Would it be possible to reduce the games like 2 conqs + 2 golds (premade team) vs 2 diamonds + 2plats (non-premade), or even extreme MMR grinding cases, 1x 2k or 3k MMR + 3x 300 MMR (premade) vs 4 normal diamonds or conqs (non-premade), by slightly changing the matchmaking? Especially for premade teams?
For example, the normal average MMR is not considered for matchmaking, but there is a penalty; they would be matched with opponents with a higher average MMR (for non-premade opponents). Or maybe, only the highest (one or two) MMR of the premade team is accounted for in matchmaking.
By doing so, we can also reduce the number of instant-quitters, those who instantly quit Team Ranked games at the start to fast drop MMR so they can lower the average MMR of opponents matched with for their premade team later. I have seen a lot of such quitters, dropping to 500 or 600 MMR or even lower, then playing with conq friends to get easy games against diamonds and plats.