When I was a freshman in college, sitting in the training room, one of the football linemen (another freshman) was sitting there and asked me what my sport was (distance running). He then asked me what the farthest run I had done was (at the time it was 16 miles). He was amazed and said "I don't know how anyone could do that". I asked him what his max bench was (don't remember it but it was much more than I could ever dream of doing). I told him "I don't know how anyone could do that". We both laughed and had gained each others' respect. The football guy went on to be a huge star in the NFL. Whenever I saw that guy on campus he always treated me with a ton of respect because my abilities were amazing to him, even though I was not a star even at the college level. I could also hold my own in an eating contest with the dude even though he was 3x my weight.
It's silly to compare sports with differing metrics of success. It's more interesting to see how tough someone is against their own competition. The best athletes are the ones who can consistently defeat their opponents or (in a team sport) consistently outperform others at their position.
It's been my experience that athletes respect each other and enjoy watching each other compete because they understand that the sport itself is immaterial and the competition is everything. Any athlete who has ever won a hard fought competition can recognize the battle of will between the competitors and will respect a winner. I think this is why we enjoy so much to compete with each other in sports we both aren't good at (see pro athletes playing golf with each other for instance). It's an opportunity to test our competitiveness with each other.
Kellerman's audience is the failed athlete, who likes to tear down a winner's achievement out of jealousy at his own failure. People who never won at any level and like to shoot down champions...