I read Jane Leavy's Sandy Koufax: A Lefty's Legacy. A great book, set up around his perfect game.
The description of the condition of his arm by the end of his career, and what he had to do to keep playing, is pretty horrific. Bob, is that what you meant by we won't see his like again? Because no-one with an arm in that condition would keep playing? Or something else?
p.s. my son read it too