Marshall's paper would have been written during the mid-1960s, just before Curt Flood challenged the reserve clause -- and as the late Marvin Miller took the reins of the players union.
Quite simply, Miller belongs in the upper tier of most transformative figures in the history of baseball. Naturally, he isn't in the Hall of Fame, primarily because of the owners' resentment of a man who enabled them to garner unprecedented wealth by first forcing them to share some of it with the men on the field who made it all possible.
I've written about this several times, and it still gripes my cookies.
Baseball Hall of Fame as corrupted banana republic: Jackie Robinson, Babe Ruth and (not) Marvin Miller.
Baseball. I love it, bit it's still an ass.
Baseball Union Chief Marvin Miller Awaits His Due, by Richard Sandomir (New York Times)
... But if (Curt) Flood, a center fielder, merited being honored for sacrificing his career for the labor rights that he believed all players deserved, the next logical question is: Why is Marvin Miller, the union chief who transformed the baseball players’ union into a fierce labor force, not a member of the Hall? Miller, who died in 2012, has been rejected by various veterans committees an absurd six times — five during his lifetime and the sixth in 2013 when his candidacy was spurned by at least 10 of the 16 voters who elected Bobby Cox, Tony La Russa and Joe Torre.