If players are evenly skilled, i don't see any problem going with group vs randoms. What i have noticed that everytime i go and play with my friend (who is something like prestige 5 and i am 13), we get x2 harder players than we get when going alone, so i think the game has emphasis on putting grouped people against eachother and soloers in different matches if possible. this is purely feeling based reply, but this is what i have "noticed". maybe i am fabricating everything in my mind, but whatever.