That doesn't make him the best boxer. It's the same as looking at Manny Pacquiao's speed and saying, "He's the best. Haven't you seen his speed," looking at Jack Dempsey's toughness and saying, "He's the best. Haven't you seen how tough he is," Tyson's Power and Defense and saying, "He's the best. Haven't you seen how powerful he is?"
Pretty redundant but I think you get the point.
joe louis, rocky marciano, cesar chavez sr., jack dempsey, marvin hagler, mike tyson, etc. all fighters who can just as easily claim the title of "greatest boxer." Ali easily takes the title of "most famous boxer" but "greatest boxer" is up for serious debate.