My views on this topic are, for what they are worth, the following:
As some have noted above, the relative importance of nutrition varies greatly according to the nature of the sport and, albeit somewhat less so, according to the age of the athlete.
I would add that nutrition potentially plays a far greater role in weight-based sports, especially ones like wrestling where the season is long, matches are many, conditioning is critical throughout the season, and where the practice cutting of weight to make oneself more competitive is widespread.
That being said, my answer to the question of whether nutrition can make an elite athlete is no. From my observations of and dealings with top level. i.e. world class, Russian and Turkish weightlifters my conclusion was that as long as the athlete is getting the minimum, nutrition plays a neglible role. I would like to think the opposite is true, but I can’t.
Genetic ability, hard work, discipline, mental toughness and expectations are far, far more important. The latter two are especially important. On other threads people have noted the importance of the last, expectations, on strength sports. Being next to someone in training or competition who makes a tremendous lift can revolutionize one’s expectations for one’s own performance and in itself can spur tremendous improvement. As they say, if you want to get stronger, find people stronger than you and train with them.
My mind is still open on the topic of the importance of nutrition for competitive sports, but in the majority of cases I think if nurtitional minimums are in place the influence of superior nutrition effect is small at best in most sports and for most athletes. Weight-based sports and older athletes being, potentially, exceptions.