Oscar was a good champion and a good Olympic Gold Medal winner, but he made his name beating little champions at their natural weight class, but not his natural weight clas. When Oscar had to move up and fight fighters more his size, he started losing and then when he finally went against fighters his size he couldn't step it up. Remember Oscar is 5ft11 fighting fighters that were
Super featherweight
Lightweight
Light welterweight
Welterweight
When Oscars true weight class should of been Middle weight and super middle weight and light heavy weight, Oscar should of dominated these weight classes but he couldn't because he wasn't that good skill wise, he had to use his size and strength advantage to destroy much smaller fighters, only to eventually get dominated by, two naturally smaller fighters in Paquiao and Floyd, who are naturally smaller men then Oscar is, go figure.
If you want to give Oscar credit for beating fighters 5 times smaller then him, then that's your choice, but i can't give someone who is 5ft11 that walks around at 180, 190, pounds naturally, beating guys at super featherweight, lightweight, light welterweight. Then moves up and can't beat fighters his own size and strength.
At least Floyd and Paquiao and other smaller fighters started at light weight classes and them also being naturally smaller fighters, were also able to beat and dominated fighters that were naturally bigger and stronger then themselves, examples.
Floyd vs Canelo, with Canelo fighting now at 160 pounds and almost beating GGG.
Floyd vs Oscar, nobody can't deny Oscar was much bigger then Floyd and Floyd could barely make 150 pounds.
Paquiao vs everyone at 147, nobody can't deny Manny was a very small welter weight fighter, just look at him body wise against Horn. also against other welter weight fighters like Margarito and others.
If, Oscar was 5ft7, 5ft8, and started off at 130 pounds and then moved all the way up to 160 pounds but only lost to middle weight fighters and finally lost when he was past prime, then Oscar would get 100% full credit and would be a all time great champion.
But Oscar is 5ft11, 5ft10, beating naturally smaller fighters which he should be beating them, being an Olympic Gold medal champion. But can't beat fighters a little smaller then himself at 155 and can't even beat fighters his own size and strength at 155 and 160 pounds.
All said and done Oscar is a good champion, that wasn't an all time great champion and can't sit at Floyd, Paquiao"s and the other all time great champions table, but only can sit, with the good champions, table of Boxing.