Write-In: Rather than leaping in behind the actual establishment favorite, John Kasich, who earned the title by placing second in NH, the establishment money forces catapulting themselves behind "Republican Obama (Rubio)" for racial reasons and perhaps an ideological quirk or two with Kasich. Once they realized Rubio was going nowhere, they had left Kasich on fumes for so long that he was utterly useless outside of Ohio (and Manhattan).
Beyond that, the major candidates either ignoring TRUMP or forming bromances with him until January for Cruz and February for the rest was really stupid. Throw CruzCarly in there as well.
Welcome to the Hilldawg train.