Also, just for the record, and I realize this is a super old post BUT, I really ike that 1921 Moose Jaw photo and even though the info is incomplete on Baseball-Reference.com I'm pretty sure the players depicted are L-R
Elmer O'Shaughnessy--Mark Koenig (obviously)--Peter Rose (the non-cheater) and Karl "Junk" Walters (he palyed throughout the Western states & Canada from at least 1913 to at least 1921--I have seen the same guy on a 1913 RPPC for LaGrande in 1913 id'ed on front as "Junk" Walters).
here are some known cards of O'Shag & Rose to compare to...
Koenig was the only Major Leaguer depicted BUT the Minor Leaguers are even more fun to me as there is so much still unknwn about these guys.
-Rhett