Because many delegates are released to vote their preference on subsequent ballots, to answer your question about the ‘delegate gap’. I’m not saying the majority of Rubio or Kasich delegates would go to Cruz, but they might, which is why the Trump folks’ claim that it will all be ‘over’ after New York is just as much wishful thinking as they say this article is for Cruz folks.
2nd ballot will get the GOP, RYAN. Take it to the bank.