I got that part. I was just looking for a reason why it is Orange with more people almost always. If it were random, then the 'crowded' LW arena should be one or the other roughly 50% of the time.
Orange is first LW arena on the list and more important: It's the TT arena. When TT is over, it's just renamed and Blue is opened. But the people are still in Orange, thus having the "numbers" advantage. To get the masses migrate to another LW arena you need a really horrid map.
Besides cap, you can rank the player's arena choice reasons like this:
- planeset
- numbers
- map
Planeset being only a marginally bigger incentive than numbers, that's why it took some time after the original arena split for people to leave EW (most populated arena back then!) and go to LW.