How does the theme of wisdom apply to The Natural?

Roy Hobbs is one of literature's greatest anti-heroes and, as such, unwise.  Blessed with great natural ability, Roy squanders two careers and his role as a father as he falls prey to women, greed, and food.  Malamud says there are no more heroes left in the modern world, that they are undermined not only by themselves, but by bloodsuckers--journalists (Max Mercy), bookies (Gus Sands), owners (Judge Banner), and--above all--women (Harriet Bird, Memo Paris).

Roy's first career as a natural ends when he fails to give Harriet Bird "wise" answers to her philosophical questions.  She asks him the meaning of life, and his response is:

Sometimes when I walk down the street I bet people will say there goes Roy Hobbs, the best there ever was in the game.

Her reply is:

Is that all? Isn't there something over and above earthly things—some more glorious meaning to one's life and activities?

Roy is clearly an ego-centric physical force who pays no regard to a life of intellect or spirituality.  Seeing this, Harriet becomes an agent of retribution who can't wait to punish arrogant men.  She shoots him out of spite.

Later, when Roy gets a second act (didn't Fitzgerald say there were no second acts?), he repeats the same foolish ways with Memo Paris.  Choosing Memo (of the sick breast) over the clear "vegetative goddess" in Iris Lemon is Roy's most unwise decision, especially since everyone (including Memo) warned him against it.  Iris, the mother of his child and the spark that ends his slump, is forsaken because she is too wholesome, to maternal, too old.

Roy's great bellyache before the big game is the piece de resistance of Roy's naivete and foolishness.  It's so obviously unwise that it's Freudian: Roy is a child who obeys whatever his sick "mother" (Memo) commands.  When he wakes up in the maternity ward, even he must have felt he was being punished by the gods of divine retribution.

After Roy throws the last game over a handful of bucks and he is exposed as a fraud, the kid at the end is incredulous: "Say it ain't so, Roy."  Even kids have the moral high ground in The Natural.