Arch-conservative Bay Buchanan forcefully makes the same point.
In reality there is only one candidate. Barack Obama. In November he will win or he will lose. John McCain is relevant only in so far as he is not Barack Obama. The Senator from Arizona is incapable of energizing his party, brings no new people to the polls, and has a personality that is best kept under wraps.
Monday Update: Actually, I'd have to say that there are two ways that John McCain can make the campaign about him. First, he can pull various kinds of stunts like his trip to Baghdad, gas tax, and townhall proposals that have the potential to make him look clever. Second, McCain can make himself a negative spectacle by giving extremely poor speeches like his New Orleans speech last Tuesday, and committing little faux pas like refusing to meet with Billy Graham. Otherwise it's about Obama.