Fastball

I reviewed Knuckleball a few months ago and enjoyed it.  Fastball (not the same production company by the way) primarily explores the question of "who throws the hardest".  How would a pitcher from the 30's compare with the fireballer's of today?   I've always thought should Justin Verlander in his prime pitched in the 20's and 30's, that he would dominate...but that's not necessarily the case.  Narrated by (who else) Kevin Costner, this documentary pleases.  Recommend.