And Iowa's right on the money? Seriously? They can't pick a winner.
The last two presidents began their road to two terms by winning the Iowa caucuses.
Iowa's polls reflect the state of the race in Iowa at this time - that's all. And no single poll should be used to argue the state of the race. Rather, you look at an aggregation of polls, and see if they generally point to a common trend. In this case, of the last 5 Iowa polls, 4 show significantly increasing his share of support and moving into the lead, while the other shows Trump and Cruz in a dead heat. So I think it is safe to say that as of last week (when most of these polls were conducted) Cruz was leading in Iowa.
Now that does not mean that Cruz will be leading in Iowa in February. Nor do the polls showing Trump leading in national polls mean that he will win any specific states, nor that he will win a majority of delegates or the nomination. Polls are not predictive - they show the state of the race at a specific point in time, and can show trends - but only retrospectively, not prospectively.