^^ this... the size difference alone gsp would never get in on him. reach advantage and kicks go to silva who knocks out people in weight classes 20 pounds heavier than him. we already know gsp has a weak chin (matt sera), with how deadly accurate silva's hands, elbows, knees, and legs are he would probably have a first round ko win.
2 wheels > 4 wheels
For those who have ridden no explanation is necessary. For those who haven't, no explanation is possible.