Fernando's run as an elite pitcher only ran from 1981 (age 20) to 1986 (age 25), and he never reached his 1981 peak again. Yet he reached a peak level of aura, that very few of his generation met and rightly goes down as a baseball legend.
I'll just pick a few Hall of Famers from that time and there are more - Jim Rice, Andre Dawson, Tom Glavine (a little later). All deservedly hall of famers, but they never reached the level of impact or aura that Fernando had in 1981 or in his early years in baseball. Fernando wasn't a hall of famer, but he is one baseball's biggest legends from the 80's.