Answer
18-year-old McGraw joined the Baltimore Orioles of the National League as a pitcher in 1890. He was signed by Oriole manager Ned Hanlon, who had seen him pitch in a sandlot game in Manhattan. McGraw was the youngest player in the National League that season. He was a successful pitcher for the Orioles, posting a 24-13 record with a 2.43 ERA in 1890.