Iowans picking Cruz, and him winning, is in spite of their choice.
He won, again, because the political landscape was in his favor: it was an off-year, his opponent made a public gaffe about gun control, and lots of conservative Californians had been moving to Texas. Cruz is not a popular politician in Texas, but because there were lots of transplants who hadn't truly experienced his bullshit, they voted for him. Couple that with often-lower turnout in off-year elections and the gun comment, and you have a recipe for a winning strategy.
This time, Cruz is on the ticket for the Presidential Election, Californians are moving to Florida, and Millennials and Gen Z are actually turning up to vote. It doesn't matter what Iowans think, and he should be worried.