Let's say it's 1125, or 112 short of the magic 1237 number. That leaves 1347 out of the total 2472 delegates who are not committed to Trump. Rubio right now has 168; he's not getting any more, maybe a couple more tops, so let's say 170 total for Li'l Marco. Kasich has 138 now; let's give him the benefit of the doubt despite his polling everywhere outside of Ohio and say he more than doubles what he has now, for a total of 276. Plus there are 5 each won by also-rans Bush and Carson, and one for Paul). That's 457 total.
Subtract that 457 non-Trump and non-Cruz delegates from the 1347 who are not committed to Trump on the first ballot, and you get 890 left for Cruz. Maybe Kasich does a little better or worse, maybe Cruz does a little better or worse, but it doesn't matter for the math purposes.
So no one wins on the first ballot. Kasich and Cruz are still in it; where do Rubio's now freed 170 delegates go after the first ballot? Shifting to Cruz (or to Kasich obviously) en masse would do nothing; if they all went to Cruz, he'd still only have 1060. Either all of Kasich's 276 and Rubio's 170 would have to shift to join Cruz's 890, or all of Cruz's 890 and Rubio's 170 would have to shift to join Kasich's 276.
That's a tall order, and you can't count on en masse delegate shifting. These aren't lemmings, they are people. Trump would still seem to be in the best position because he just has to peel off 112 somehow. Where does he look? IMHO Cruz's 890. Trump has to start working now to make those connections, so when/if the time comes, things will fall into place.
Good analysis post 13