there might already be lists out there. People post compilations of arena data all the time in the WoW forums. It might be as simple as knowing our team names and polling that data which might be much easier then hitting the arena. I'll see if I can find it.

Edit:
Findings
http://www.sk-gaming.com/arena/ Global rankings for teams over 2k rating, a start but not quite what we are looking for.

That's All I could find but I wasn't looking that hard because I suck at arena.