Cruz was focusing on Rubio, if you recall. The days leading up to the caucus were full of Cruz ads attacking Rubio. The general consensus among the Trumpees was that Cruz had lost Iowa and was fighting Rubio for second. As it turns out, Cruz won Iowa with daylight (no doubt projected in internal polling) and was fighting off his biggest challenger, Rubio, who had the big momentum and posed the biggest challenge.
Had Cruz not switched his focus to Rubio in the last few days, Trump may very well have come in third.
Your comments are all hypothetical. And factually, there wasn’t much daylight when all three were in the twenties. Cruz should have been the perfect candidate to run away with IA and truly stake out the social conservative vote. Had he hit mid thirties and up, possibly he could say, “Rally around me.” But Cruz can’t because the numbers indicate Cruz is locked in a threesome. And, if Cruz isn’t solidly in the top three in NH I would say he might be finished.