All the campaigning Trump did in OH was not wasted. He won along the PA border. Kasich was forced to spend most of his time winning OH, and as a result was very weak everywhere else.
Now Trump has to spell it out, how Kasich is a Democrat on most issues. Trump hasn't been speaking out on the big bank influence, and how Kasich's other career was at Lehman, where he succumbed to that agenda. And he's got to let folks know just how bought and paid for Kasich is.
100% for Trump here.
Given the crossover votes in Ohio it is entirely possible democrats voted in the republican primary to support Kasich, who is basically Hillary without the pending indictments.
Ohio had a byzantine process whereby voters had to actually select two groups of delegates for their candidates. That could mess things up. Also, supposedly, Kasich’s team was in cahoots with Dem union leaders and the like, who helped to prop up the Kasich vote in order to thwart Trump.