Your math is faulty. If Donald gets 1237 then he gets the nom. We agree. But if nobody gets 1237, then all those with delegates have chips to bargain with.
What did Kasich get last night? 14% ... in a blue state ...
Almost no one will vote for someone who cannot get to 1237. In two weeks Cruz support will tank. He will fight with Kasich for the bottom 20% ...
No one will vote for the second place guy who cannot get there.