That's not part of the posed shot: Dude actually hit like that. And not just hit, but hit for decent power, totaling 37 HRs in 1962.
Daddy Wags's Baseball Reference Page Sponsor not only mentions the hand placement, but also the tragedy of his later life: he died homeless and alone. Again, coming off of Thanksgiving, just reminds me how thankful I am for the things I have. Hardballtimes also has a great writeup with some really choice quotes from the man himself. For example, despite his circumstances, Daddy Wags referred to his predicament as a radical lifestyle choice, like the hippies. Not only could Tim Lincecum learn a thing or two from Daddy Wags about what it takes to be a real hippy, but there's a dogged optimism in that statement, one that refuses to give in to self-pity against all odds. In one way or another we could all use a little Daddy Wags like that.