Mario won two PAC-12 championships in the worst P5 football conference and did nothing with them. If you win your conference and don't make the CFP, that's underachieving. The dude's second PAC-12 championship team also lost to Iowa State in its bowl game.
If you win the Sun Belt, you aren't making the CFP no matter what. Billy didn't underachieve with his seasons, and both of his teams won their bowl games. Mario is also 9 years older, so. I don't really care about the rest of this post. It'll happen, or it won't. I'm not making definitives on either before the first full season and recruiting cycle are done.