Caveat, I have NO inside information, just speculation. So, take it for what it's worth.

I'm guessing that maybe Burgess and Pope didn't see eye-to-eye on a variety of things like Xs & Os, in-game strategy, recruiting priorities, maybe even their personalities didn't mesh as well as either one hoped. So, when the opportunity at Utah presented itself he took the opportunity to gracefully extricate himself.

But, perhaps, he really had come to love BYU, its players, and what the school stands for, as well as its close connection to the church, while he was an assistant at BYU. So when KY reached out and shared his philosophy and approach he was ready to return.

Like I said, ALL speculation.

Regardless of the reasons, I'm glad to have Burgess back!