The caucus format only helps Trump and Cruz. How are you going to get Jebio or Kay-sick voters to actually make an extra effort to vote?
It all depends on keeping turnout as low as possible. If Trump and Cruz can’t get their voters out, but Bush or Rubio can, then Bush or Rubio will take a larger proportion of the vote.
Again, the way I see it is that all the campaigns see it as being to their advantage to keep turnout low and mitigate against wildcards. Understand that this is a gamble all are taking.