I would say olympic 800m runners as they to need to combine sprinting prowess,endurance,pain tolerance,patience and diffferent race tactics....There have not been many dominant/consistent 800m guys in the sports recent history which tells you its a very technical event which needs fine tuning.....Golf is a little like this as well.....
With the recent threads appraising Toney's legacy, I think this bears repeating. Toney got to the highest levels of the heavyweight division of the most physically grueling sport in the world while borderline obese. And small to boot. He pulled it off because he was simply vastly more skilled (and, honestly, tougher) than his opponents. The grand table of sports difficulty puts it nicely in perspective, IMO.
There’s so many ways to define athleticism and all of them have their place. To me, NFL wideouts are the tops. They have to be fast, be able to jump and have keen upper and lower body control at the same time (almost ballet-like to stick the feet inbounds whilst concentrating on catching a ball). But I watch the top 10 plays of the day during baseball season religiously to see some of the ridiculous infield and outfield plays that are made. Some of those are absolutely breathtaking.
Tennis Players are up there. It's the perfect blend of endurance, balance, being explosive and co-ordination.
110 metre hurdlers and 100 m sprinters are probably the most finely tuned. The smallest of small changes in terms of their training, preparation, nutrition and rest are all combined to make a potential increase of 0.1 - 0.2 improvements on all their overall performance. There bodies are balanced to create explosion a slight change in their body can be the difference between winning by 0.1 and loosing at the elite level. Definitely not the fittest or best athletes overall, but in terms of finely tuned so either of them.