I'm a big supporter of persistent large scaled arena roleplays. There's a few places the previous one crashed pretty hard, besides the points made already. So if you'd like to hear my humble suggestions to fix these issues in the future; 

- Stick to one planet/location/realm; Having different locations is all well and good, but I thought it was way more of a hassle than fun to come up with reasons why any of our characters were sticking around in the places they were. Simplicity over complexity when it comes to locations and geography, please. Faction building is a lot easier the more compact the world is. Rather than "There's some empire sixty thousand lightyears away that will never threaten me, or the faction I'm loyally fighting for? Well, okay. Uhm." 

- Perhaps introduce an actual in-game arena? Along the lines of what League of Legends (and similar games) have done? Could solve the issue of "Why are we even fighting!?" when they're put into a fight specifically to defeat their opponent. This is an ARENA roleplay after all. Plots and stories could carry out outside of these, and fights wouldn't neccesarily have to be restricted to that, but it's nice to have the option. A sort of in-world accepted "This is where people go to fight, because reasons."

These are just suggestions of course. I have no idea what you have in mind, and I'm probably up for it regardless.

Also, please, please, please, 10-tier scale?

Edit: Oh, you already thought of the League of Legends thing. Nice.

Edit Edit: Setting-consistent world would be nice though. Characters tweaked slightly to (fluff-wise) to co-exist within the same setting is much more fun and interesting than a big heap of special snowflakes that couldn't be more out-of-this-world if they tried. Again, in my humble opinion.