Let us choose to be matched with 4-man premades or not.
When queuing up, maybe add a checkbox to either allow or not allow you to match with / against premades that are 4-man (with). Since these games are abnormally more difficult on the solo member since the 4 man usually just disregards them, and the opponents are working together since balancing makes them more likely to be a 4 or 5-man premade. I dont mind having the occasional 3-man premade since then at least there is one other solo player, but 4-mans suck to play with.