Several polls also showed McCain competitive in OR and MI. We all know how that turned out in the end....
Remember, McCain withdrew his campaign from Michigan in mid-September, effectively handing the state over. I remember one poll some time around March that showed him tied with Hillary and losing to Obama here, and another one later that showed him beating them both. Then Obama took the lead in nearly every Michigan poll after he secured the nomination.
Because McCain was seen as a more moderate, conciliatory conservative, he would have won in any year before 2008 by a solid margin. But by the time he was nominated, nearly the entire country had come down with severe Bush Derangement Syndrome, and his chances were almost entirely shattered. He took the lead after the convention, but then the financial crisis destroyed whatever chance he had left.