5 Man Premades vs. 5 Man Randoms
Let's be honest here. A good number of us add people to our friends list after we both do real good in a game. This use to lead to Duo Queue and we were "punished" by having to face higher MMR or other duo queue opponents, the thought being that we've practiced together or we're on curse/skype together.
More often than not when I'm playing in this dynamic queue as a team of 5 none of us have practiced together or are on skype/curse. I only do a 5 man queue with them to reduce the risk of an AFK/Troll/Dodger. There is no direct skill advantage aside from knowing that "hey, you did real good in that game that one time.. let's play again". So this whole team of 5 vs. another team of 5 isn't 100% necessary. Especially if it leads to longer queue times. I'll take the 98% and hope that after a certain length of time in queue it just starts match making with what ever is available.