They all use dedicated servers or a Matchmaking system. The equivalent in wow would be premade and single queue option based on skill rank. These are what work for the top selling games out there.
They should just have a queue rated BG that only allows queued people and a random rated BG so people can play the flavor they want. You want to have a guild dedicated to PVP great do that, it will be just like every dedicated server with guilds in countless PC shooters. You casual and dont care about having to make the best of a team of perfect strangers great you get your Matchmaking system similar to what Halo does and you never get pit against premades so it's more fair.
If they implemented it like this dollars to doughnuts the premade side of things would be a barren wasteland and the matchmaking would be king, why? Because people are sick to death of trolling trade LFG, LF GS 5500+ spamming for 30-40 minutes of their 2 hours they had set aside to play that day then finally get a group and have half leave if they lose thats why. This system is doomed to failure you cannot regularly organize 15 skilled people without pugging or being in a stupid guild with rules that often encroach on your sanity and personel life.
This is exactly the thing alot of PVP'ers wanted to avoid like the plague and why they stopped raiding and moved to BG. Please blizz look at what the vast number of people are talking about here we do not want Guild officers telling us if we are qualified to play on their rated team or not. We want to queue with similarly skilled player quickly and efficiently just like in Left for Dead, Halo, Team Fortress, Modern Warefare and countless other games out there. We want a Matchmaking system!
If you toss the "Hardcore" a rated queue system fine go ahead they can bang their heads against a wall and us people with real lives can laugh when they show up in rated BG randoms gripping about how they sat there for an hour spamming trade to fill slots for the last 5 people from their guild that didnt show and finally gave in to the system that works...