Not sure, Nebraska doesn't win a lot of close games? I don't think you can just point to one score games as a litmus test of how good a program or coach is.
For instance, 2012 they won 4 of 5 one score games which is great, but also lost 38-63 to Ohio State, 31-70 to Wisconsin and 31-45 to Georgia. Then in 2016 they lost 5 of 6 close games, but was ranked as high as #7 in the country, went to a bowl game and was the last Nebraska team to be ranked at the end of the year. Without a deep dive into the numbers, you can make the stats say whatever you want.
In my mind, its not debatable that the Nebraska Football program is getting better with Coach Frost, the players are getting better, recruiting is getting better, the facilities are getting better, the coaching staff is getting better, and eventually the number of wins will get better. What's debatable is how long it will take, but I'm confident over the next four years with Coach Frost we are in great shape.