Well I will admit that I only read the first couple pages because I have med school finals to prepare for....but this is a thread I can relate to.
I started in high school a freshman not making the varsity team for cross and by senior year was doing 90 mile weeks and becoming one of the top runners in the state. I was SLOW for short stuff, I mean slow. I didn't have the 'talent' In college I consistently worked up to 120-140 miles and 6:00 pace felt like nothing at all. I became a 24:45 cross runner. I know I don't have the most 'talent' that most people will say but I also know I have some of the best talent of a distance runner, discipline and perserverance.
Sure there were more talented guys that barely lifted a finger and could beat me, hey that's running, it happens. But I can still look back and realize that there were still people that wished they could be like me too, they trained hard and tough and just didn't reach it.
In summary, everyone has a limit or a cap and talent does play a big role in it but it's always hard to find that cap. One also has to remember that hey, maybe they aren't doing the training that would benefit them the best, that their body would respond to the best. Overall, people don't have long enough running careers to find the maximized training system for themselves, but many get lucky and after the first few tries find one that's pretty damn close and they blaze some times and get remembered.
In the end everyone in running that is competitive will realize and have to live with the fact that no matter what you do there will always be someone better than you that does a hell of a lot less (and just for these board people, except Bekele etc.)