In my opinion the use of "best" and "second" best athletes is unfortunate - seems like there's stereotyping going on there. Where would Jim Thorpe fit?
I can see the argument for adding an asterisk next to the statistics for the seasons of any player who played in a league while discrimination or war was taking place. It would be a lot of asterisks (Babe Ruth, whoever won batting titles when Ted Williams was serving, etc.) I tend to think the great players would still be great against the best competition - we'll never know for sure.