When Jason Kenney created the UCP he set up the preconditions for the party to get to where it is today, and its eventual demise. What do I mean by this? Kenney may have believed that he could control the extreme elements in the UCP in much the same way that Harper did so as leader of the CPC.
Harper allowed the extremist factions in the CPC to exist and even to have something of a voice in the party, but at the moment that a given push looked like it would have a political cost for him, he would shut it down. This was done through a combination of tools - Harper exercised considerable personal control over the party apparatus. That meant that in large part, if you kept him happy, your career was secure. The leader's office had the power to quash constituency decisions such as new nominees, and the "public face" of the party was carefully protected. So, while the extremist wings of the CPC could make a certain level of noise - it was never enough to do more than keep their followers believing the party was aligned with them.
However, Harper was able to do this because the Federal CPC is a much bigger entity than the UCP in Alberta - and although the Prairie Reform rump of the party clearly dominates it today, the party needs votes from outside the Prairies in order to have any hope of ever forming government. Harper understood this, and was very careful to keep the extremes in check even though his own leadership depended on them.
A party of the scale of the UCP is a much different animal, and that's where Kenney's choices failed.