I hadn't heard of "The Batting Stance Guy" until this morning, but he's surprisingly accurate. He was on Letterman last night, and supposedly can imitate any stance in baseball history.
On Letterman, he started out with impressions of Manny, Big Papi, and Cal Ripken, and then moves on to Rickey. The Rickey portion begins at approximately the 5 minute, 30 second mark of the clip. Enjoy!