Symbolism, Imagery, Allegory
If you don't think that baseball and Moby Dick have anything in common, well… okay, you're right. But for sheer literary allusion's sake, The Art of Fielding is chock-full of references to Melville and his Moby Dick.
It all starts years before the book begins, when Guert Affenlight (then a student at Westish) finds a letter from Herman Melville and writes his research book, The Sperm-Squeezers, about life on fishing ships in Melville's time. That's the connection: fishing ships = baseball. Both are made up of crews of men who normally wouldn't hang out, but they're drawn together by a common purpose—either a white whale or a white baseball.
There are a couple of explicit Moby Dick shots, too, like when Affenlight refers to the house he's going to buy as "a big white whale of a house" (59.4), which honestly makes no sense. It's not as though Guert has been chasing this house forever, or that he's never going to catch it. He buys it less than five pages later, just like that. Take that, Ahab.
Still later, Mike ruminates, "If he was the Ahab of this operation, this tournament the target of his mania, then they were Fedallah's secret crew" (74.23). If you care to unpack that allusion, we can help.