Medar was a careful and thoughtful coach who saw a pitching future for Maddux. Rather than teaching Greg to throw a curveball, which can seriously injure young arms, he showed him how to throw a changeup at the age of 13. Sports Illustrated quoted Medar counseling Maddux that, "The changeup is not going to be a good pitch against high school hitters - you could just throw your fastball and get most of them out - but down the line a good changeup is harder to hit than any other pitch." However, Maddux was doubtful that he would ever make it as a major league pitcher and told Sports Illustrated that at the age of 15 he preferred hitting.
Nevertheless, Medar was convinced that Maddux's true talent was pitching. He told the young player, "You're probably never going to throw hard enough to overpower people." Then he showed Maddux the pitch that would eventually bring him overwhelming success in the major leagues, a fastball with sidearm delivery created by gripping only two of the baseball's seams rather than the usual four. It is not the fastest fastball, reaching only an unremarkable 87 miles per hour, but tends to veer away from left-handed batters in an unpredictable way. Sadly, Medar died before Maddux graduated high school and never got to see him deliver the pitch against major league hitters.