I think a clear theme developing is the amount of success the 'plucky fighters' are having. Japan, Saudi, Ecuador, USA spring to mind.
I don't mean to disrespect those teams, as they can play well in bursts, but they play with aggression that has rarely been allowed on the international stage, coupled with immense energy, means that a new style is being allowed to flourish. Basically, those traditional big teams that aren't on top form are really struggling. England dodged a bullet, Germany and Argentina didn't.