Trump narrowly missed getting the most votes because some of his supporters stayed home. Not his solid supporters. But those on the fence. We’re only talking a couple thousand supporters.
Not attending the debate was the right move for Trump. But I would guess that the fence-sitters were influenced by Fox News’ slanted coverage and their agenda to get good ratings for the debate that they were hosting.
Trump’s childish attacks on Cruz probably had little influence on the fence sitters. Those attacks didn’t help Trump, but I doubt they hurt him. Rush has been pushing the “11th commandment” for decades, but it doesn’t apply here.
Also, Rubio flooded the state with effective flyers and TV ads. One woman said that at her caucus young men mentioned that they were registered Dems but switched to vote for Rubio.