You have to think his campaign was imagining a scenario in which they inherited his dad's supporters and all their insane zealotry passion and enthusiasm, but also brought in more mainstream or moderate Republicans, especially the young ones. Sound a bit less strident, compromise on a couple key issues, and you can patch together a viable coalition. Instead it's all gone the other way.
Would be interested in seeing who former Ron Paul voters are supporting now, but answers to "who did you vote for 4 and 8 years ago?" tend to be really unreliable so we could never know.