Not a complete waste, but James Toney is up there. If he got his big baloney eatin butt in shape he would be a top HW contender and/or turn CW into the JT division.
Riddick Bowe and Zab Judah. Both had the talent and skill sets to be ATGs at their respective weight classes...Im talking top 3...yet neither had anything close to the mental makeup to put it all together.
Tucker came along at the wrong time. He never beats Tyson and would never be seen as the top guy. Although he definently could have been viewed as the number two guy of the era.
Probably Andrew Golota. in his Prime he had it all a good jab, power, decent movement for a big man etc. He did not have it mentally however.