Coach. Kentucky is a results based job. BYU is much less interested in results than UK.
Being a high ranked team and not winning championships or going deep into the post season will be seen as a failure at Kentucky but not at BYU. There's a reasonable chance he succeeds at UK.
Is he a great coach? If he is it comes with the caveat that Dan Marino, Charles Barkley, John Stockton have, a lack of post season success. This is the exact reason the Kentucky job is open now.
Is he great fit for the UK job? Doesn't matter he has it and while this time and place is unlikely optimal this could be his only chance at it so he had to take it.
I'll be watching to see how it turns out.