I'm kind of conflicted on his HoF candidacy. It is true that without him, there is no Miami football as we currently know it. His ideas about only recruiting South Florida and the Miami area were so ahead of their time. However, he was there only 5 years and left right after the title, then was underwhelming at every other place he coached. He ended up with more all-time wins than someone like Fulmer (158 vs. 152), but unlike Fulmer he had 151 losses to go with it. He was essentially a .500 coach.
Everybody remembers his time with Miami, which looks even more impressive in hindsight given what Miami eventually became, but he didn't do much after that. If he stayed at Miami and had more success (not even necessarily more titles, just success) or if he had success at another school(s), then it is a no-brainer.