The tradition in Iowa may be to join the caucus and take in what everyone knows about the candidates. Some have seen the candidates on the stump and some have done the work to understand what they bring to the ticket. Most of them are sitting back in cruise control; letting others do the work for them. Independents are usually in the undecided category.
And having said that; a narrow win here won't mean much as so many people are so undecided.
I think the following states will see things firm up for support.
Many of the Paul votes for instance; will be protest votes. People want to send a message by voting for him. I don't think the seriously want him as President.