Probably a rig issue with the point numberings, just to make it clear by point I mean what is called a vertex in maya:
In 3D each point has a unique number attached to it, the numbers can change arbitrarily when you change the geometry, since polygons do not have a native order or directionality the number change is often not predictable.
Point numbers are used all over the place with all kind of operators and its why you often find deformers or rigs behave differently after editing geometry. In games rigs, very simple offsets are used to drive skinning using the transforms of the joints, essentially each point is assigned to a joint, then that point is displaced to the correct position based on the animation.
If a point hasn't been assigned to a joint (which would easily happen if the point numbering has changed) it will not be able to find it at all so the point is never moved from the world origin which is why all the points are in the same location.
You need to re-bind the rigging and export it.
Also a little hint with the addition of detail, only add edge loops / detail that will add more information to the silhouette, by smoothing you are subdividing which will add polys that do nothing to help define the model.
Hope that helps
FX supervisor - double negative