It means that if you cannot find a fight in one arena, there are two others to try - i really like the change. I like the variation in planeset too.
I do not like the milkrunning attitude in the EW/MW though, be nice if it was set to 20 troops to take a base instead of 10. Too often i log on to see one team with 5 players, and one with 30, and the 30 are just hording the smaller teams bases.