Peck and Snyder did not join together till 1868; this is a fact. Therefore, forget trying to date the card pre-1868. Also, the George Flanley reference as "now Captain" sounds not like he is captain when the card was issued, but rather at a point in time they are talking about in the text.
My view is that all the team cards were issued in 1870 or later and that the Creighton card was issued as a commemorative, possibly on the anniversary of Creighton's death in 1872.
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