[taneq]

That's kind of the point. "Deliberate practice" definitely helps to hone particular skills which fill holes in your overall competence. When you're performing at ultra high levels, you probably already have optimal performance in most areas, and all you have left to practice are particular skills.

Also, how you measure "sports performance" and what a percentage point means at different levels seems crucial to the whole thing. Maybe deliberate practice only accounts for 1% of performance... but an athlete who's 99% perfect is twice as good as an athlete who's 98% perfect.