Even if they have a lack of talent it doesn't have nearly the lack other teams have and yet do better offensively. If teams like Western Michigan and Colorado State can have the offense they do with the talent they have vs teams like Alabama and USC, BYU should be doing better vs LSU and Wisconsin. Even Utah State had better offense than BYU vs Wisconsin. Statistically USU did much better in many defensive category as well.
Coaches can have a bigger impact than talent. Rich Rodriguez and Brady Hoke are examples of people that did worse with more talent than Harbaugh did when he came into the program. He took over multiple teams and immediately had success at EVER team even USD.