1.) He is 31 years old, the youngest head coach in the country.
2.) He has no track record of success. Nobody even knows anything about him, as a coach. He has never taken a struggling program, and built it back up to success. He isnt established as a coach in any way, shape, or form. He isnt really known to do anything except recruit good players to Arizona. Again, he has no track record of anything except being a good recruiting assistant.
3.) He took over a job that was probably the most well oiled machine in the country at Memphis. They destroyed that league year-in and year-out under Calipari. Nobody even had a chance at them, really. First year under Pastner, they go 10-6 and upset UTEP to make the NCAA Tournament.
He isnt ready for a big job like OU... OU needs a guy with a proven track record of success, a guy who has built up a program, who has a track record of success, who will bring an identity with him, etc. Not some 30 year old guy who has about 10 months of head coaching experience in his whole life.