BYU is not his alma mater and I don't think he's suddenly developed an emotional/spiritual connection to it strong enough to sway his job selection. Whether its Craig Smith's future, the chance to work with KY, the relative directions of the program or a view that he might have a chance at the head coach spot at BYU sooner than at Utah (or factors completely different than these), the most likely reason is that he sees this as a better step right now for his career — which is how most people make most job selections.