Fighters with tons of amateur fights who improved technically as pros?

Thomas Hearns had like 112 amateur fights and IIRC like a dozen or less KOs.

Emmanuel Stewart said when Hearns turned pro he realized he wasn’t closing his first when he punched, so hitting a guy with a limp hand instead of a brick, and they addressed it.

Now Hearns was a helluva boxer (I don’t think anyone every outboxed him, including Ray Leonard) but he definitely improved as a puncher in the pro ranks. I’m also sure it was more than just closing the fists but also adding muscle, standing ground and digging in and throwing for power rather than just points, but he improved as a puncher by quantum measures as a professional.

 

I would think, in recent times, that Oleksandr Usyk could be the poster boy for this.

 

IMHO: Oleksandr was an excellent Amateur boxer. But, as a Pro, he's learned to fight with a polished professional style, including ring position awareness, defense, including more head movement, harder jabbing, more power shots, and he sits down on his power shots now, and knows better when to load up (making them much more effective).