Referring to any fighter who manages to win a world title as a "one-hit wonder" is misleading. To even get into position to challenge for a title, a boxer has to beat other ranked opponents, usually over a number of years.
But, there is a boxing equivalent to the music industry phenomenon. Just like certain artists manage to rocket up the charts from obscurity and become ubiquitous for a few months, only to never be heard from again, sometimes an unlikely contender will have a night for the ages, capture the belt, then lose his first defense and fade back to the level of journeyman, or perhaps, even vanish from the sport.
The term "one-hit wonder" has negative connotations that I frankly don't really understand. Most of the world is comprised of no-hit wannabes and spectators.
It's true that a few of the names on this list are guys we might have expected more from. So part of their story is tragic: they showed that tantalizing glimpse of true greatness, but for whatever reason, couldn't hang on to it.
But for even more of these fighters, that one night of glory was a real-life Rocky Balboa moment, the one time they rose up over their heads and did what almost nobody thought they could do. No matter what came after, it's still a moment that can never be taken away.
And I know a lot of day-job working musicians who would be thrilled to have some one-hit wonder residual checks coming in.