Solich and Pelini have been mediocre or slightly better HCs after their stints in Lincoln in smaller schools. This to me is the best indicator of why they were NOT the 'best' hires for NU and never could be. Nebraska is one of the top ten football programs of all time across all levels of college ball. There is no reason we should be hiring head coaches who have little or no previous heac coaching experience at a division one level. Frank had plenty of assistant coaching experience and decades of time watching and working with many of the better coaches in football (Devaney, Osborne, McBride, and dozens more). He was literally handed the keys to the then best program loaded to hilt with the best talent etc. Within 5 years, Frank's lack of recruiting was readily apparent to all who wanted to see. I would argue that there were several assistants on Tom's 97 staff who were far better choices than Frank.
As for Pelini, he was intriguing but his lack of Nebraska 'ties' turned out to be his major shortcoming and, along with his temper tantrums, became his undoing. Bo was a good defensive mind certainly, although he seemed far too focused on pass defense instead of stopping the run first. In the big ten, particularly, you have to be able to stop the run or you're in trouble. After a couple years with some exceptional D linemen, it became problematic and eventually chronic. The pressure got to Bo I think and he lashed out negatively - perhaps because he never really did have a Husker heart.
Bo and Frank both end up in Ohio at lesser schools where they are enjoying themselves coaching average football teams in average leagues with average results. Neither were ever seriously considered top national head coaching prospects in my view and it is really hard to argue their resumes were anywhere near that of a fully qualified HC for Nebraska. Riley and Callahan both had better resumes but Callahan is an NFL coach and a dam fine one - he is NOT a college level coach. Riley may have been the best coach for Nebraska of the three - had he been hired at the time Tom retired. He would have been younger and capable of taking the reins of top program and continued it longer than Frank or Bo or Callahan, although he would ultimately have failed to sustain the program as well.
For better or worse, we are where we are for a variety of reasons. There is no one single person to blame for Husker football's downfall. Hindsight is 20-20 of course. I personally was "OK' with Frank's appointment although I was very apprehensive about his ability to maintain the program. I didn't know much about Calllahan at the time he was hired and didn't care for his west coast style of offense and he was too offensive minded and therefore left the defense on the back burner too long. By time Pelini came in, there was very little real Devaney/Osborne legacy remaing so Pelini was likely in abit over his head without the head coaching experience. Bo is not a leader or administrator nor an executive. He is a defensive assistant/coordinator - period. He could have taken McBride's spot and Charlie would have been a better HC candidate although, once again, he may have lacked the requisite head coach experience. Tom took over with Devaney at his side for a decade. Frank took over and Tom left town. Not fair to Frank either.
How many championships have Pelini and Solich and Riley and Callahan won, combined (before, during and after) becoming NU's head coach? I don't have to research the answere to know it is most likely far less than Osborne won as HC. Arguably, therefore, NONE of them were the 'best' hire for NU.