Trump has brought in brand new caucus goers that may not be reflected in these polls. It will be up to him to get them to the caucus.
It's not a bellwether, nor is it definitely non important either. When a tiny niche candidate wins Iowa, like say Santorum or Huckabee, it's meaningless because they are folks who will never go above their tiny niche. Both Trump and Cruz have support across the spectrum, excluding the hard core establishment types - so if they come out of Iowa 1-2 in whatever order - it's significant.
Things changed dramatically in the last four weeks in Iowa last go round....mainly fueled by the six against one (Newt) ad blitz. Who knows if something like that will happen this time around. But I could see Cruz winning Iowa and Trump winning NH, and then it's all about South Carolina, which it often is.
Cruz does need to win Iowa in terms of momentum that will help him in New Hampshire, where a win will be tougher.
An Iowa win sets Ted up for South Carolina later in February and the southern states that follow March 1st and March 8th.
Trump could shuck his third wife and marry an Evangelical. That type of personal example might prove he’s one of them.