I think he is recruiting better than his predecessor, but doesn't know how to effectively run a football program. Either Kalani isn't great at hiring the right guys/leading his coordinators, he isn't great at establishing a competitive culture, or holding players accountable. Regardless of which reason it is, you can't be a good football coach if you are missing those elements. He isn't great enough at recruiting to overcome his shortfalls.
We can try to point to the limitations/bureaucracy/funding of the organization, but even with those issues, BYU should be better than 70-80th best team in FBS, which has been the norm for the past 3 season, with 2017 putting us as a bottom 20 team. BYU has more resources than all of about 50 teams, so as a baseline a coach has to at least be in that range and then you hope they can overperform that.
BYU S&P Rankings (Avg 75, Avg of 91 if you exclude season 1 before the football culture was destroyed)
2016 - 28
2017 - 107
2018 - 67
2019 - 98