To me athleticism, has always been based on natural ability. With training and practice "natural athleticism" can be developed. There are many that have natural gifts, B.J. penn being one of them. GSP is an athlete, and has natural ability. With the development of those "gifts" he is now a super-athlete. Think about those guys you took gym class with when you were young...the guys that always excelled at anything BEFORE training. It doesn't have to be huge muscles, or explosive takedowns...just people that are ahead of the average curve in physical ability IMO. There are people who can become athletic as well...I am one of them...average with lots of work, but have to work harder than those who were born with it.
Fighters I enjoy watching:
Quinton "Rampage" Jackson
Joe Rogan NutHugger...and proud of it