Nog had arguably the GOAT chin, GOAT recovery and he had very good boxing. I wouldn't be worried at all about Nog. I would be more worried about Ngannou having a heart attack trying to keep pace in a 10 minute first round. Ngannou would get eaten alive by all the good grapplers back then like Barnett, Ricco, Coleman, Erikson, Randy, Mir, Fedor, Nog, Werdum. He would also be an underdog against strikers like Aleks, Sergei, Cro Cop, Schilt, Hunt, Pedro, Yvel. I would also favor the next generation guys over Francis like JDS, Cain, Roy, Ben, Carwin, Brock. Even Kongo might be a good fight. Ngannou is a rookie compared to all those guys