It was not the loss in Michigan which has been the cause of major heartburn to Bush supporters. It was the amount of money spent in Arizona. Political pros know there are a lot of reasons you win or lose a campaign.
Campaigns are very complex systems - like the weather.
As much polling as you do, as much radar data as the Weather Service collects, sometimes you get surprised. Spending money on advertising, however, is wholly within the control of a campaign. General Eisenhower did not ride around on tanks with George Patton. He stayed back in London to be able to understand the entire European Theater of Operations. Karl Rove is a very, very smart guy.