You should probably look at your rig in Blender - Unity uses a maximum of 4 bones per vertex, depending on your quality and animation settings only 1 or 2.

• Your settings are too low (only 1 bone affects a vertex) - looks like only the hips influence the vertices.
• Your vertices get influenced by too many bones in blender, which is no problem there, but is a problem with Unities rigging system.