While I understand the premis I don'tknow that I agree with it. I think basketball might support what he is saying because I believe most of those players learned their creativity on the court by playing on courts that were not coached. Conversely i believe our baseball players on a whole are better than they were 20, 30....years ago. The average HS player now is better than the average Hs baseball player from years ago and I think the present day player has received more coaching and instruction which would not supportive of his premise.
The last thing that doesn't support his premis is that our soccer players are so much better than years ago.
In every sport the kids now are better than the kids twenty years ago. The training for each sport progresses. The players progress with the changes in development. Many college players are now more physically developed than Ted Williams.