This question goes both ways.
Whether a super talented boxer who ended up with a mediocre career, or somebody who you feel had talent that didn't add up to the level of success they had.
First name that popped into my head was Chavez Jr, that bastard. Legit, still one of my absolute faves, but such a waste of space, despite the amount of fan fare and support he has... or had. I doubt he has any left now. He is having the kind of career now that his dedication deserved, but up until Sergio beat his ass, he was on fvcking fire.
Who you got?
Gavin Rees was an overachiever who at 5'4 won the wba super light/ junior welter championship.
Underachiever has to go to Audley Harrison. Superheavyweight olympic gold medallist who took the padding off his chin and turned into a lazy losing lump.
For over-achievers, Marcos Maidana. Guy was a mess, technique-wise. Got dropped by Khan, went life-and-death with Soto-Karass, schooled by Devon Alexander. People overrate his Floyd fights, as if they were somehow victories. He mobbed the guy like an ape and was treated like the reincarnation of SRR. To his credit, his awkwardness was an asset there and he did have good conditioning. But, he went much further and got more credit than a guy with his skillset ever should have.
As far as talent that never reached it's potential, the obvious answer is Brian Sutherland. He stent his prime years fighting on the streets and was the victim of trickery and sabotage in his pro fights.
Shawn Porter
He's a B level talent at best, but the discipline and work ethic instilled in him by his father allows him to compete with A level fighters. His heart and conditioning make him extremely dangerous. I'm not sure we'll see anyone EASILY beat a prime Shawn Porter. You fight Shawn, you gonna feel him.
Darnell Boone
first to floor p4p no.1 Andre Ward in his career
first and only man to beat and KO Adonis Stevenson
first to stretch kovalev to a decision, and a split one at that
and to think this man has a negative record of 23-24-4, yet he had the skill to do the above
I second the nomination. Boone has given the three best LHW's all they could handle and was a routine sparring partner for GGG. Pretty impressive for a guy with his record......
Darnell Boone
first to floor p4p no.1 Andre Ward in his career
first and only man to beat and KO Adonis Stevenson
first to stretch kovalev to a decision, and a split one at that
and to think this man has a negative record of 23-24-4, yet he had the skill to do the above
I always liked Kevin Mitchell a lot as a fighter. On his day he was a classy operator and a really nice boxer with a bit of everything.
I don't know if he could have maximised his talent more but I've never been so sure of a fighter winning a world title tilt than in his first effort against Katsidis and then his second effort Burns still surprised me.
In today's world of multiple belts and regular titles etc to think he never won one shocks me a bit.
Paulie Malignaggi. Guy is 36-8 w/7 KO's and was stopped inside the distance 5 times, yet somehow made millions of dollars and kept his name relevant in boxing (regardless of his commentator job). Got beat every time he stepped up to an A-level opponent. Can't think of anyone else with that resume who is as successful or warrants as much attention.
Victor Ortiz should have made far more of himself. Conversely (and of course he's an amazing athlete too) B-Hop did his absolute maximum, micromanaging his entire life and focusing his ridiculous boxing brain to lengthen his career.
Dmitry pirog, awesome fighter/wizard but had a career ending injury.
https://youtu.be/QKD7SvVaQQo
https://youtu.be/FWttlU6SFdA
Andrew Golota, he was a beast with physical tools and some skills but big mental problems. Should/could have been a hw champion twice in his fights with riddick bowe
https://youtu.be/w0xjHO0NVc8