What made Gerry Bertier so special to Yoast?

Bill Yoast never had a son and Gerry Bertier lost his father growing up. Gerry started staying after practice and asking to accompany Coach Yoast and others to scout other teams. Coach Yoast said Bertier was not the biggest, strongest or fastest athlete he ever coached but he had the greatest "heart" and desire to win. Yoast coached Bertier in Wheelchair athletics after Bertier''s spinal cord injury.