Mike Trout
On April 17, 2015, Trout became the youngest player in MLB history to reach 100 home runs and 100 stolen bases. He was 23 years and 253 days old when he reached the milestone, passing the previous record-holder, Alex Rodriguez, who had achieved it at the age of 23 years and 309 days in 1999. Trout led off the 2015 MLB All-Star Game with a home run, becoming the fourth player in All-Star Game history to do so. For the second year in a row, Trout won the All-Star Game MVP Award, becoming the first player ever to win it in consecutive years. On September 22, Trout hit his 40th home run, becoming only the second Angels player to hit 40 home runs in a season. Trout led the AL in WAR for the fourth straight year.
Frank Chapman (baseball)
Chapman had previously been known to baseball historians under a different name; he was originally thought to have been a player named Frederick Joseph "Fred" Chapman. The listed birth date for Fred Chapman was November 24, 1872, which would have made the pitcher 14 years old when he made his appearance against the Blues and would have made him the youngest player to ever pitch in a Major League Baseball game. In March 2009, SABR's Biographical Research Committee unveiled research from member Richard Malatzky which showed that, based on data from the Sporting Life newspaper, that it was not Fred Chapman who pitched against the Blues but rather a player named Frank Chapman. Subsequent research by Malatzky, published in October 2009, revealed further information on Chapman, including information about his family and that he was from Newburgh, New York; Malatzky also found evidence that he died in Newburgh as well.