I really can't rmember if I have shared this or not but there had been some discussion in the past about whether that was Lou Gertenrich himself on the back of his own baseball card set. It certainly looks like the other images of Lou. This would be a bit significant as Gertenrich was never actually pictured on any cards himself during his playing career which spanned from 1901-1905, so in a way his card back would actually be the closest thing Lou would have to an individual card (for those needing a card of every player to appear in a major league game).
Anyways, here is the full-sized image that was used on the back of the card, notice that it is actually a batting shot that they airbrushed out the bat to make it appear like a throwing shot...
Anyways, I thought it would be a cool addition to this thread.
-Rhett