Fighters who were expected to be nothing but club fighters and journeyman but proved

[cotto16]

Everyone wrong end went on to become good fighters past or present?

[Cuauhtémoc1520]

Mickey Ward and Antonio Margarito come to mind.

[butterfly1964]

Rocky Marciano definitely comes to mind.

[StarshipTrooper]

Larry Holmes. "Couldn't get it done in the Olympic trials, oh he's just Ali's sparring partner."

Poet

[TheGreatA]

Mickey Ward and Antonio Margarito come to mind.

One of the funnier moments in the sport.

[Kid McCoy]

Jimmy Young, went 7-4 in his first 11 fights, but went on to beat Foreman and Lyle and, arguably, Ali, Norton and Shavers.

[mickey malone]

Steve Robinson...

[Steak]

Saoul Mamby
Pipino Cuevas
Freddie Pendleton
Buster Drayton
Carmen Basilio

are the ones that come to my mind

they all started out with rough careers, but became world champions and beat some very good fighters.
all VERY good fighters at their best. they all seemed to fall apart toward the end of their careers too, interestingly enough.