Successful presidents come from two molds: visionaries, or mechanics. The visionaries -- think Reagan or FDR -- see what others can't and say 'Why not?" to inspire the country. The mechanics -- think LBJ or Eisenhower -- know the ins and outs of government and are able to harness the power of millions of humans to accomplish great things, or at least keep the wheels from coming off.Nutting bases his conclusion on McCain's history. McCain has no significant accomplishments not given him by his family or his wealthy wife; He is intellectually quite shallow with no real expertise in anything except self-promotion; He has demonstrated no real leadership in the Senate and is unlikely to be able the get Senators, either Republican or Democratic, to work with his if he becomes President; McCain is in may ways still living in a fantasy version of the 1960's; and he has no principles on which he has not reversed himself in his effort to be elected President.
McCain fits neither style. He's neither a dreamer, nor a detail guy. His major accomplishment, in Vietnam and in the Senate, has been merely to survive.
It's hard to argue with Nutting's analysis. When you take a serious look at John McCain, there is simply on "there" there.