I guess this is a spoiler for the story:
Spoiler Below It's a rigged carnival game. Wilt never actually misses, the balls are purposely too big for the baskets, which he discovers eventually (although he doesn't realise it was done on purpose, he thinks it was an honest mistake on the part of the guy who runs the game - who gives him a frog to shut him up when he offers to fix the "faulty" baskets).