I read the book and what he was saying was that the number of fatal incidents by pilots with 350/400 hours was roughly the same as pilots with 1350/1400 or 2350/2400 hours. The only big statistical jump was in the 50-350 hours range.
A lot these seemed to be caused by pilots with that number logged, thinking they could fly well. (JFK Jr for example).
There's old pilots and there's bold pilots, yada, yada, yada.