If you consistently good opposition, you're bound to have some tough fights, and usually, some defeats. But there have been many instances of very good/great fighters being dominated. Foreman-Frazier 1 Jones-Toney Chavez-Rosario Hopkins-Trinidad Mayweather-Corrales Pacquiao-Barrera 1 Starling-Honeyghan Sanchez-Lopez 1-2 Hearns-Duran Hearns-Cuevas
Quite strange how if you read from the bottom upwards it would be quite close to being how many people see the best heavies of all time ranked.