If this is a nail one and the 2" is where the lip of the enclosure is, the problum is from you not just removing all the drywall and only cutting it back just enought to fit it in.
The flange around the unit sticks out away from the wall so if you do as the other poster suggested the patch would be tipped and to flimsy to tape and mud.
I use lattis to shim out the studs just enough so the drywall lays flat.