Why isn't Howard Schnellenberger in the CFB Hall of Fame?

I'm not familiar with the CFB HOF eligibility criteria, but Schnellenberger turned Miami on the brink of folding into a national championship winner in 1983.

Outside of Miami he also took Louisville and FAU off life support.

• Louisville: At Louisville, he elevated a struggling football program to new heights, including a Fiesta Bowl victory over Alabama in 1990.
• Florida Atlantic: He was instrumental in the very existence of Florida Atlantic football, raising significant funds and serving as the first head coach, leading to early successes like a conference championship in 2007.

I'm sure this has been asked before, but if someone knows why I'd love to know more.