When I opened the original in Blender and focused in on the sphere I got the same odd cube.  Grabbing and moving some of the vertices showed that the faces are still there they are just folded over onto each other.  Whatever progam you use to scale the sphere instead seemed to collapse it.  I believe Cage is right about Poser using the original shape to determine the smooth angles, as the faces are 90 degrees or sharper they appear faceted when it is morped back to a sphere.