Goudey Question: Why Is Ruth on the Mound?

[robw1959]

Some have speculated that he decided to pose for a camera shot of him swinging the bat while on the pitcher's mound because he started his career as a pitcher. I get that, but yet Lou Gehrig is also swinging his bat on the mound on his two '33 Goudey cards.

In the absence of any factual information, my best guess is that Yankee outfielders of that era improved their fielding skills when Ruth and Gehrig hit baseballs to them from the pitcher's mound during batting practice. Fences were pretty far from home plate back then (typically 450' or more), so maybe those outfielders could gain quicker reaction times when tracking those balls?

More information would be appreciated, because it is a bit of an oddity to see a batter swinging from the pitcher's mound on a baseball card.