There are many valid points on the 'talent and or coaching' question in here. There are always coaching 'errors' and misjudgments and strategy and scheme issues in every game. Adjustments in the alignments, blitzes, reads, etc etc etc are a part of every game, whether going well or poorly, for both teams. Sometimes, though, talent or the lack thereof are the biggest reasons that schemes, strategies, adjustments, alignments, blitizes, etc etc don't work or are not even attempted. The coaches recognize, after careful analysis and scouting of their opponents, what may or may not be viable in the upcoming game. Riley and his staff have been around a long time and, while nobody would argue they are the best of the best, they certainly are not the worst.
We have some good players on our team but clearly not enough to win championships (we haven't won any for two decades and literally dozens of highly paid coaches. Solich certainly was of t'he "Osborne" tree and had many years of experience as his right hand man and assistant HC to learn all he could possibly learn from him. He was handed the team on a golden platter with the best, deepest, most 'talent laden' team, maybe ever!. He had a tremendous staff of assistants with many years of experience and players with all the confidence in the world. Yet, somehow it didn't work out. He failed to maintain a top ten program and in just 5 years, the best ever become 'mediocre' according to many football experts inside and outside the program. We saw it on the field in a -7-7 season and a bowl trip to Shreveport! Following that disasterous season, Solich opted to fire most of the Osborne legacy staff members - apparently to try to shift the blame for the lack of talent on the staff. Maybe there were health issues etc but the big problem was Frank was not paying attention to business and was not 'a closer' and often didn't recognize talent when it walked in his office. Frank's problems were mostly 'talent' but of course not bringing in and developing that talent is coaching. So it was both back then.
Callahan, it was hoped, would provide an immediate rush of recruiting of the nation's best once again to quickly restore the order before the Nebraska brand and 'legacy' of greatness was lost on a whole bunch of H.S. players. About 7 years is as long as H.S. seniors will likely recall a given program's on field product personally. We are now facing nearly 2.5 times that long and most high school players don't have any personal clue what Nebraska football really was like. Callahan didn't understand the college game and never really would have figured it out. He had a pro mentality and while he was exceptional skilled as an offensive line and play calling coach, he didn't pay any attention to defense. Defense wins championships while offense sells tickets.
Now we have to make the long slow climb and will have to find that magical mix of a handful of special players (the Fraziers, Phillips, Peters, Wistroms, etc) that can take us back up the steep slope. In the end it is recruiting, recruiting and recruiting - speed, size, strength, desire and HEART - are required. Husker heart is brought in from the local recruits (scholarships and walk ons). It is essential to get the effort to win the games against opponents with comparable talent. We lack all of the above.