As Rush Limbaugh himself admitted, the "rules" were put in place last August to "grease the skids" for the GOPe's designated insider, and to specifically exclude "outsider" threats.
It simply turned out to be the case that, after all the insider candidates were squashed like insect by Donald Trump, the GOPe had to designate Ted Cruz as the darling insider.
Thus, Cruz was enabled, by the party apparatchiks and their manipulation of the process, both formally and informally, to steal all the delegates.
Rush Limbaugh himself admitted that this "greased skids" scheme was what benefited Cruz, and not some great "ground game".
Vote Trump
I hear him justifying the Cruz plan...but that it didn’t work.
I think if I was Rush and had embarrassed myself as much as he has in the past few months, on the day Trump unquestionably becomes the presumptive nominee I’d just shut up and play music instead.