Here is a quick food for thought. Iowa is not your typical State when it comes to voting. Unlike the standard ballot box style most states have where you stand in privacy making your anonymous vote, the caucus style adds a level of peer pressure. So here goes my theory on why Trump Lost Iowa.
In the last several election cycles, the winners of Iowa tend to be the religious evangelical voters. Now my theory is that this crowd adds a lot of peer pressure on who you can vote for. Trump has a wishy washy past with some issues evangelicals would be in an uproar over, particularly abortion.
So the stigma of going over and picking Trump is harder in a Caucus. This is why Santorum and Huckabee were able to win the last two times. It was a show of who is more evangelical than the next. So in my eyes, the bottom line for Iowa is that it is irrelevant who won, but definitely relevant for who didn’t win.