Kill/Escape based MMR could work
As it stands, the SBMMR system currently evaluates MMR by treating every match as four simultaneous 1v1 matches between the Killer and each individual Survivor. This means that a Survivor who dies will always lose MMR, regardless of what they did during the match. This doesn't seem to sit very well with a lot of people, myself included, but I don't think it has anything to do with it being based around kills/escapes. I think it could be salvaged by evaluating MMR by actually treating matches as they are: 4v1.
If the Killer kills more than two survivors, the Killer should gain MMR and the Survivors should all lose MMR. If the Killer kills exactly two survivors, neither the Killer nor the Survivors should gain or lose MMR. If the Killer kills less than two survivors, the Killer should lose MMR while the Survivors gain MMR.
This system could work for a few reasons:
- It would reward Survivors for keeping the Killer busy, whether it be through extended chase or getting camped, by still rewarding them with MMR so long as their teammates work on generators and escape
- It would remove the pressure from Killers of losing a potential 4K to the hatch because, regardless of whether of not the Survivor finds it, it would still be a win for the Killer
- It would overall discourage facecamping by making 1K matches detrimental to the Killer and 2K matches not worth anything, which is healthier for the game on both sides
TL;DR: When it comes to the SBMMR system, more than 2 kills should be a Killer's win, less than 2 kills should be the Survivors' win, and 2 kills should be counted as a tie between the sides.