Born in St. Louis, Missouri, Ruel began his professional baseball career at the age of 19 with his hometown team, the St. Louis Browns, appearing in 10 games during the 1915 season. He then played in the minor leagues for two seasons with the Memphis Chickasaws before joining the New York Yankees in . With the Yankees, Ruel shared catching duties with Truck Hannah from 1918 to 1920. He was the Yankees catcher on August 16, when a Carl Mays' pitch hit Ray Chapman on the head, resulting in Chapman's death the next day. He later defended Mays and said that he was innocent of any wrongdoing.