Maniac pretends that Giant John McNab once pitched him the "stopball" because he doesn't want John to be disgraced in front of his little brothers.
Giant John had been known as "the fearsome fastballer", and had been trying to set a record for the greatest number of consecutive strikeouts one day when Maniac first showed up in Two Mills. John had struck out thirty-five batters straight, when Maniac stepped up to the plate. Maniac was able to hit every pitch that John threw him except for two which almost hit him, and had even hit four home runs over the fence (Chapter 7). When Maniac later meets John's little brothers, and the two boys realize that he is the legendary player who "had blasted their big brother's fastballs to smithereens...it (takes) a good five minutes of rolling on the sidewalk to get all the laughing out of their systems". Maniac, not wanting John to be embarrassed, offers him a way to save face by making up a story. He tells the younger McNabs that the next day, John had pitched to Maniac again, this time using his "secret pitch", the "stopball"; according to Maniac, he had not even been able to hit a foul ball on the pitch which "comes right up to the plate, looking all fat and easy to belt, and then, just when you take your swing...it sort of...stops...and your bat just whiffs the air" (Chapter35).
Maniac had gotten the idea for the stopball from Grayson, who had once been a professional ball player. The stopball was "the only one left in his repertoire from the old days"; and as Grayson described it "she's gonna float on up there, and just about the time she's over the plate, she's gonna stop". Maniac had never been sure how much of Grayson's story "was blarney", because although the pitch was very slow and acted rather peculiarly, he never actually knew "if he was swinging at the old man's pitch or at his speech". Whatever the case, in weeks of practicing with Grayson, he had never been able to hit the ball out of the infield (Chapter 26).