So, I'm just gonna be blunt about this from the get-go -- I'm a casual.
First Arena ranking (yes, I can't remember the name of it): Gold 1
Second: Gold 1
Third: Platinum 1
The others aren't ranked (mostly because I'd rather play Warzone Assault than FFA, but hey, I already told you I'm casual), and there's only one thing I've noticed about ranks are that if you play "hard" enough, you can actually rank.
Yes, I forgot what rank it was, but it DID move up (excuse me for drinking while I play, I find it to be more fun), obviously one of the gold's to 2.