By the thread description, you're asking about the worst boxers who were/are in the upper echelon, right? Under that criteria, my vote would go to former heavyweight champion Primo Carnera, who is generally regarded as one of, if not the, poorest of the heavyweight champs. He came in at a very low ebb in the division, and there's issues about him being propped up with fixes. He was said to have been a gentle, decent person.

I have to take issue wth some opinions about Jerry Quarry. He fought in an era with some of the most talented in boxing history. He beat many top fighters except the greats at the very top, such as Ali and Frazier. He just wasn't quite good enough to win the title, but again, it was an era loaded with talent. A tragic figure, too, as he stayed in too long, suffered from dementia, and died in his early 50's. I had the honor of seeing him box when my dad took me to see the match in Oakland, CA, 1968, when heTKO'd Thad Spencer during the elimination tournament held after Ali was stripped of his title. The man could box and could punch.

Chanteyranger