Mark Pope has never been involved with a big time program as a coach. He has spent 1 year as Director of Operations for Mark Fox at Georgia and 1 year as an Assistant Coach for Jeff Bzdelik at Wake Forest. Neither coach is a great coach and both seasons were bad seasons. Then he went off to Utah and has been there ever since. He has only been to the NCAA Tournament twice and never won a game. He hasn't recruited big time recruits.
There is absolutely nothing in this guys resume that says he's worthy of coaching at one of the top schools in the nation. Yes Kentucky will throw a wad of cash at kids, but so will Kansas, Duke, UNC, Illinois, Xavier, Arkansas, Missouri, Indiana, Arizona. It is not like Kentucky is the only school that has money. Maybe he's Mr. Charisma and can sell kids, but they're going to know the coaches at the other schools. Those coaches have years of experience talking to the top kids.
Another thing, he's been at BYU or Utah State for the last 13 years. He hasn't been at big programs. Who is he going to get for assistants? Is he going to be ok with guys he's unfamiliar with or is he going to want to bring his guys? It will likely be a mix, but that creates the risk of issues with your staff.
The problem is not that he's not a good coach. He certainly appears to be above average. The problem is that he doesn't appear to be a great coach, and he's going to a school where they expect greatness every year. After their last Elite 8, Calipari went 25-6, 9-16, 26-8, 22-12, 23-10 and they ran him out of town. They're not going to settle for 20 win seasons. And on top of it, the SEC is a stronger conference than it was 5-10 years ago. With Barnes at Tennessee, Oats at Alabama, Pearl at Auburn, Williams at Texas A&M, Paris at South Carolina, Beard at Ole Miss, Gates at Missouri, Calipari at Arkansas, and Golden at Florida you're going to need to be more than above average to bring Kentucky fans the amount of wins they expect.