His players were taylored to the scheme he was running. Sure, there was some adaptation to the QB (Hill to Mangum)
I'm not bagging on Bronco. I generally think he did a great job. Mistakes were made, but nothing that would sink the program. But, he didn't leave the program in awesome shape when he left. 2016 would have been a disaster without Taysom and Jamaal — BYU just lucked out that they BOTH came back. Even you admit that there was a thinness on depth in many areas. And Bronco WAS the coach when Doman was the OC, so I don't get that excuse.
Sitake is learning on the job. Major mistakes have been made, but I feel that many of the major concerns have or are being addressed. 2018 was far better than 2017 and 2019 will be better as well — even with the front loaded schedule.