Cruz doesn't need to overtake now. Slow and steady will win for him. The more important thing that you are obviously missing is that Trump adapts Cruz's policies and even his words. Then Trump flattens the media with them. Along with helping Trump, that helps Cruz.
I think Trump could easily win this and I am fine with that. But Cruz will win if/when people tire of Trump. And that will be awesome.
I would think after 6 months of bluster and attacks on everything from McCain’s military record, stopping new Muslims arriving, Mexico is sending is rapists and criminals, Trump should have imploded 50 times. Now it is scant 3 weeks to first primary and Trump is still the front runner.
There is something going on in the country which career politicians and media are failing to comprehend.