4 is the most that can be in a premade as of now. I have one as 14 merc numerous against a foursome of 50s ... but when they que as a group and are on vent its can be difficult in say huttball if your team is all over the map.
Right now the distinction is how many of these guys are in a voicechat. If they have 4 50s you take it and move to the next one not come to the forums say its broke.
By the way, you have the option to do the same you know.