I think a lot of people are marginally attached to the cycle and say they like Trump and will vote for him but just aren't going to vote at all.

Also half of the voters are open to changing their minds. Probably a good proportion of Trump voters will learn more on the night of caucus about him than they have since, and not vote for him. As well as the anti-Trump crowd is likely to move more towards Cruz than anybody else so to give Trump a loss. We should not expect a Rubio or Carson surge, and it is likely that Trump will underperform. We should maybe expect a Cruz surge.