Living in Arkansas, I think I can give a pretty good evaluation...
In Nutt's first three or four years, he actually did pretty well. Won the Western Division at least once, and at one time had Arkansas in the top 10 for a season.
Having said that, he did it using players recruited and coached by previous staffs...
Since then, Arkansas has been mired in mediocroty or worse. The year Nutt was under consideration for the NU post, he had a pretty good year - beat Texas in Austin and beat Mizzou in a bowl game. But as noted, that was primarily due to Jones.
If folks think Steve P. is a used car salesman, they ought to get a load of Nutt. For all the acclaim he's received as a recruiter, the staff routinely bring in below-average classes. This year was an exception, and only because the four members of the "Springdale Five" (which included Mitch Mustain and Damien Williams) signed. And they signed only after their high school coach was brought in as offensive coordinator - originally, only two committed, and of those two, Mustain retracted his committment for a time. For those that are not familiar with Arkansas geography, Springdale is a whopping five minutes from the Fayetteville campus. Yet Nutt and staff couldn't get committments from those kids until he brought in their high school coach.
What's worse, he routinely builds his staff with mostly second-raters, which means players rarely improve. When Arkansas was actually something of a power - in the 60s and early 70s - then-coach Frank Broyles hired assistants that were dying to be head coaches. We're talking about guys like Jimmy Johnson, Barry Switzer and the like. Even under Holtz, the coaches were folks who were proven - for a time, Monte Kiffen was the Defensive Coordinator/Linebackers coach.
Nutt doesn't do that. He has three or four guys that have been with him most of his career. They want to move on to head coaching positions, but nobody will consider them - and guess why? This year, Nutt hired his first assistant with NFL experience...
Butch Davis over Nutt is a no-brainer. Callahan over Nutt? Well, all I can say is thank God Nutt declined/Pederson never offered (which ever it was). Nutt would have made Solich at his worst look great.