How did Jeffrey Magee hit the world's first frogball for a fourbagger in the book "Maniac Magee"?

Jeffrey Magee appeared one day at the Little League field, just as John McNab, a giant of a pitcher, was showing off his stuff.  He had made the players standing around after the game take turns attempting to hit his famous fastball.  He had struck out thirty-five in a row, when Jeffrey stepped up to the plate.  Amazingly, and to McNab's chagrin, Jeffrey connected with his pitches, at one point hitting four home runs in a row.  Seething with frustration, McNab lobbed a frog up to the plate.  Not wanting to hurt the frog, Jeffrey executed a perfect bunt right in front of the plate.  As McNab lumbered foolishly after the frog, who was hopping playfully and erratically around the field, Jeffrey circled the bases for an "inside-the-park-home-run bunt" - he had just hit the "world's first frogball for a fourbagger" (Chapter 7).