Yeah, about those baseball metaphors.... Sorry about that, Chief.
At one point in the episode, former ballplayer Kenny Powers was wallowing in self-pity in the room he had at his brother's house. And there on the nightstand by his bed, close to his head, was an issue of Playpen Magazine.
Other shows in which Playpen has appeared:
'In Plain Sight'
'Homicide: Life On The Street'
And those are just off the top of my head. I'm sure you can find the full list at Wikipedia.
What? I have to lead you there by the hand? Big babies......