We will soon see if this “ground game” theory is true, or just another traditional axiom that has gone out the window in the Age of Trump.
But the real point is, Trump doesn’t need to WIN Iowa, just be in the top two spots, based on analysis of Iowan winners who have gone on to become the nominee.
Trump will no doubt do that. Cruz desperately needs to win Iowa or his campaign is essentially over as Trump will win NH and SC. For Trump, a win in Iowa just shortens the process.
Trump (or any other high-profile candidate) doesn’t really need Iowa at all. He committed to Iowa because there were too many doubts about his serious intent. Trump seemed serious in the 2012 campaign and jilted his supporters.