When players have rib injuries/fractures, most of the time the side or the area is not identified or identifiable. In Tate's case, everyone was given a great look on TV as to exactly which side and which area the rib injuries occurred. Flak jacket or not, he may as well be wearing a target on his chest for Ds to be honing in on where to stick it to him. Besides that, it is important to understand that ribs are considered to be part of one big ring originating from the vertebrae. A hit upon anywhere within the circle will lead to movement throughout the circle, including in the area of a fracture
. That is why sleeping laying down (no matter what position) still puts stress on the circle as a whole and therefore upon the fracture site(s).