There is a piece in Moneyball where Lewis is recalling a story Bean tells him about the difference between Billy and Lenny Dykstra.
"Physically, Lenny didn't belong in the same league with him. He was half Billy's size and had a fraction of Billy's promise - which is why the Mets hadn't drafted him until the 13th round. Mentally, Lenny was superior, which was odd, considering Lenny wasn't what you'd call a student of the game. Billy remembers sitting with Lenny in a Mets dugout watching the opposing pitcher warm up. 'Lenny says, "So who's that big dumb ass out there on the hill?" And I say, "Lenny, you're kidding me, right? That's Steve Carlton. He's maybe the greatest left-hander in the history of the game." Lenny says, "Oh, yeah! I knew that!" He sits there for a minute and says,
"So, what's he got?" And I say, "Lenny, come on. Steve Carlton. He's got heat and also maybe the nastiest slider ever." And Lenny sits there for a while longer as if he's taking that in. Finally he just says, "horsefeathers, I'll stick him." I'm sitting there thinking, that's a magazine cover out there on the hill and all Lenny can think is that he'll stick him.'"
The point about Lenny, at least to Billy, was clear: Lenny didn't let his mind screw him up. The physical gifts required to play pro ball were, in some ways, less extraordinary than the mental ones. Only a psychological freak could approach a 100-mph fastball aimed not all that far from his head with total confidence. "Lenny was so perfectly designed, emotionally, to play the game of baseball," said Billy. "He was able to instantly forget any failure and draw strength from every success. He had no concept of failure. And he had no idea where he was. And I was the opposite."