This creative, enigmatic set of paper-thin stamps shows star players of that decade in familiar poses, pitching or hitting. It is hard to find a more significant pitcher than Christy Mathewson, who had already notched nearly 350 wins by 1913. The known images from this set appear to be connected to a monthly calendar issued around the same time, hinting that further research will one day reveal a complete story of its design and distribution. The current SGC population report shows just four total stamps graded for Mathewson, making this one of the toughest singles offered in our auction.