Posted By:
identify7To answer your question, Ted:
No. There is no rule which is universally accepted which can “tell you for certain that this is considered his true rookie card”
Being that it is a Postcard... It is a card.
I can tell you for sure that there are a lot of folks who do consider it his "true rookie card."
Although some folks will never consider a Postcard to be the same as a "real" baseball card, postcard back Exhibits are collected with the same enthusiasm as those without the postcard back.
Personally, I think the Postcards are COOLER when they are USED.
I would love to have a Cobb Postcard from that set that was postmarked in 1907 with a cool old message written on the back!!