What is the importance of the story of the stopball in  "Maniac Magee"? 

Expert Answers
Jamie Wheeler eNotes educator| Certified Educator

Chapter Seven, the story of the "stopball" reveals how "Maniac" got his nickname.  (A "stopball" is one pitched directly over homeplate.)

McNab is the fearsome Little League pitcher, an unparalleled softball champion. Jeffrey Magee stumbles into one of McNab's games.  But Jeffrey doesn't know that no one has ever been able to hit McNab's best pitches.  Jeffrey, uninformed and unafraid, fearlessly takes the mound.  McNab is angry; this scraggly, unknown kid has already bested him by hitting home runs.  Now McNab was ready to do his worst.  He pitches his blindling-fast frogball. Then McNab began

cackling away, and the kid at the plate was bug-eyed.  He'd never -- nobody'd ever -- tried to hit a fastfrog before."

To McNab's (and everyone else's) shock,  Jeffrey not only swings, he connects.  Enraged and humiliated, McNab threatens the interloper, bellowing:  "Don't stop til yer outta town, runt!  Don't let me ever catch ya!"

Chapter 7 ends with this line, "And that's how Jeffrey Magee knocked the world's first frogball and four-bagger."  Chapter 8 begins, "And how he came to be called Maniac."