During his four years as head baseball coach at the University of Michigan, Rickey, who years later invented the batting helmet, had designed the batting cage, which he conceived to help catchers like him, who had less time to hit because they were busy keeping balls from sailing away whenever their teammates swung through practice pitches. He also invented the sliding pit—a dirt patch where runners could perfect their approach to the base—and a system of strings that gave pitchers a primitive form of feedback as they aimed for the edges of the strike zone, helping them hone their command.
