The 2016 team had a terrible record, but was actually much better than advertised.
The main fault of the team was laid squarely on the defense, specifically, Brian Van Gorder's awful playcalling. Who else would call a cover three scheme play after play after play, while opponents are eating us alive with the short and medium passing game? The only other defensive coordinator that we had who was nearly as foolish was Jon Tenuta, who kept calling jailbreak blitz on every down...
That defense cost us at least 4 games that year, easily. Special teams also contributed to another 3 games lost.
I do agree with you, though, that the offense could have pulled off maybe two more victories, if Brian Kelly hadn't tried to placate Malik Zaire, who was constantly clamoring for more time. Kizer deserved to be the unquestioned starter, and playing an ineffective Zaire for all of those series in the Texas game cost us that shootout. We were scoring at will with Kizer at the helm.
That being said, Brian Kelly definitely learned from his mistakes, and has certainly evolved over the years. He started out as a big time small potatoes coach (Grand Valley State, Cincy), only to be overwhelmed once he got to the big stage. However, he finally got rid of the cancers on the coaching staff (Van Gorder, Longo), and learned the value of having competent assistant coaches to the point where he's an excellent coach on the big stage now.
There's no question about who's leading the team on the various fronts, and Brian Kelly has been able to squeeze out every last drop of performance out of Ian Book that one could reasonably have expected.