Posted By:
RobertSDan--
Some of the Postaco stamps feature players identified as Federal League, I believe. I think I have a scan of one of those Federal Leaguers somewhere which I'll hunt for.
As such, wouldn't the issuer have identified the player with one of his major league teams (either before or after his Fed. stint), instead, if the stamp were issued in the 1930s?
And the stamps don't ID the players with their final teams, as this Cobb stamp from OldCardboard.com can attest (it IDs him as star batsman, not as manager (which came later) and not as a Philadelphia A):
Also the stamps ID some -- like Claude Hendrix -- as a "star" pitcher, which, by the 1930s, all would agree he was not considered as such.
Also, I found this reference to Postaco on a stamp collector site, indicating the company issuing baseball releases from 1910 to 1915:
http://www.personal.psu.edu/staff/c/r/crr2/turtstmp/update.0109/
Anyway, nothing definitive, but it appears to me as if the 1915 date makes sense.