A couple of articles on the topic.
Drag0nista in Crean, Rudd and WTF? explains what happened in the non-spill of March 2013. It's probably the best analysis I have seen up to now.
Josh Bornstein, an employment lawyer, explains in When you understand hate, you understand Rudd's fall why so many of Kevin Rudd's colleagues hate him and thus would rather lose than make him leader again.