Looking at the octgn images, since I don't have the physical cards on me, it seems that two of the formations (Fire at Will and Form Ranks) do specify "in this zone" for the secondary ability, while the other two (Dig In and Press the Attack) do not. Without that specification, the understanding would be that location doesn't matter, i.e. the effect is Arena wide.
I do believe that this is an oversight though, given what formations are supposed to represent and how the other two work. I would definitely play them as only affecting the zone and expect them to get an errata to match that. Until then I guess it's a matter of RaW vs RaI.