Your anecdotal musings do not match with the numbers. Kaisch received less than 114K votes in the entire state of Massachusetts. It defies logic that 50K of those were from cross-overs.
I don't believe many registered Repubs were voting for Kasich. His support had to come from crossovers, new voters, and "center-left" independents who can't stand Hillary. The GOPe Repubs, of course, voted for Rubio.
Trump, no doubt, got his big boost (about 50,000 more votes than "native son" Romney got in 2012) from independents and new voters. This was quite an achievement - especially considering the competition was much tougher in 2016 than in 2012.