Miami will continue to struggle regardless of who coaches.
Back in the 90s and early 2000s Miami's selling points were: easy schedule, exposure, championships.
In today's college football, everyone is on TV, everyone has internet, everyone has exposure. Conference affiliation is more important now than before. You need the conferences to generate revenue for you, but you also need to generate revenue for yourself. Miami has a very small number of donors, boosters, etc. that support the football program. On top of that they have no stadium of their own with premium seating of their own to generate revenue. The fan base is ultra fickle meaning that at the first sign of trouble the income dries up.
Miami will continue to have this problem until they have their own stadium AND expand their fan base. Look at the list of big-time donors and boosters at Texas, Bama, Auburn, UF, etc. (thousands to tens of thousands) compared to Miami (dozens to perhaps a couple hundred).