If you are good at swinging something a bat or golf club, it's going to transition well to distance, but not necessarily playing a round of disc golf. Katchz is the semi-pro you are referencing, he was also a long ball golf competitor with some ridiculous club head speed like 130mph, so his pure swing mechanics have been honed quite extensively, that's Jamie Sadlowski territory. Throwing far is not the same as playing competitive disc golf, I think he was playing around 950 rated disc golf. That's a far cry from beating the top pros. The mental game is bit different in disc golf/ball golf than other sports than are more reactionary.
On the subject of throwing far and being an athlete, I don't think you need to look much further than Christian Sandstrom or Ville Piippo. Sandstrom competed in high level fitness competitions and has extensive knowledge in bio-mechanics and won something like 10 straight distance titles. His record was beaten by David Wiggins who is also very athletic, I think he had baseball scholarships lined up but decided to go pro disc golf. Wiggins record was beaten by Lizotte who is perfectly built to throw far and he is also very athletic. Ville was an Olympic javelin thrower and holds the world record for the longest cell phone toss. Sandstrom and Ville have never been able to compete with the top pros despite all their athletic prowess and distance.