Non-heavyweight boxers who led successful careers despite looking extremely unpolished and/or lacking refined technical skills?
Sakio bika .terrible to watch but effective.coggi Argentine LWelter .Odd cagey stile but held the wba title for.a few years sometimes with the refs help!.Pat cordell funny crab like defense but took Sanchez the distance in Mexico no mean feat!.
Victor Galindez, Julio Cesar Vazquez, Castro, Coggi, Roldan.... Argentina has a production line of mini Firpo/Bonavenas
To expand on the point I made, prior to my hilarious joke, regarding Argentinian fighters. Most of those I mentioned had huge upper bodies for their weight division. Coggi, Castro, Roldan all had great barrel chests and comparatively skinny legs. Their power came from their strength rather than correct technique. Maybe the physical disparity between upper and lower body physique mean they lacked the co-ordination necessary for timing the snap of their own punches or they lacked the footwork to be able to time their opponents and be in the right range, I;ll leave that for others more knowledgeable than me to ponder. It's just an observation, rather than an informed view, on my part.