Photograph By AP Photo/Larry Goren
Harper is set to become just the 12th teenager in MLB history to appear in the postseason. After making his debut in April, Harper slumped a bit during the middle of the year, with his second-half OPS getting as low as .717 on Aug. 15. But he hit .327 with 12 homers in his final 44 games to show the world what all the fuss was about. If the Nationals advance, he'll turn 20 on Oct. 16, smack dab in the middle of the National League Championship Series.