Wakefield was a first basemen and the AA pitching coach discovered he could throw a knuckleball, they almost released him but, after his success on the mound they used him.
The knuckleball doesn't mean that you can't succeed with normal stuff, Phil Niekro got scouted on his slider and curveball originally and then he threw a k-ball and a coach told him to keep throwing that. Charlie Hough is the only person I can think of in the MLB who threw it because of arm troubles.
I'm sure a higher percentage of the knuckleballers at tryouts get scouted than conventionals because, there aren't many knuckleballers and almost everyone is a conventional pitcher.
Charlie Haeger and CHarlie ZInk were scouted on 92 MPH fastballs and they just picked up the knuckler, now Haeger's at the big league level, now though both of them have about low 80's fastballs but, the knuckler works for them.