Take my example: to find a fight in EW or MW, I must be on the lower number side or, at least close to some action. That means that it doesn't matter the chesspiece I'm playing for, I must look at the roster and choose what suits better my objective.
I was playing for Bishops for years. Yes, for years. Not because of any kind of loyalty to the chesspiece but just because... All my known foes where on the other sides, many players I knew were on my side. There was a habit. Also, I was more of an AvA regular, not visiting much the Main Arenas. Then, I got a bit tired of it and I started to visit EW and MW, leaving LW for tank mayhem or instant gratification...
What happened in EW and MW was that, as the numbers dwindled numbers got so low that it was very easy to get unbalanced. The 5 or 6 versus 2 is annoying but when the fight is on the other side of the map... it becomes obvious that you have only one option: you milk or you change sides.
Also, I have encountered more often the milk-runners and land-grabbers attacking the lowest number country - preferably with no opposition - for points and glory. Again, you could choose to be on the same side, play alone on the other side of the map, go to another arena or, as I discovered, change sides and create some kind of opposition.
And you know what I found out? I have fun. I have lots of fun. Most time I am desperately defending a field, sometimes I attack and attempt to capture bases in numerical inferiority, by surprise, break adversary's momentum... I do have fun.
Defection? Maybe. I would call it evolution, perhaps. In order to survive, you must evolve. And if that means changing sides, we do that. Itīs a game, not life. And you change a lot in life, too.
Cheers,