With the Reds from 1917 to 1926, the left-handed hitting Roush never batted below .321, and was an instrumental part of the team's World Series championship in 1919. He won the National League batting title in 1917 and 1919. His best career year in batting average was 1921, when he batted .352. He also led the leagues in Slugging average (.455) in 1918, in Doubles (41) in 1923, and in Triples (21) in 1924. He was renowned as having the best arm of any outfielder in his era. He held out most of the 1922 season over a salary dispute that continued into spring 1923.
Roush played for the New York Giants again from 1927 until 1929 and rejoined the Cincinnati Reds for a single season in 1931 before retiring. He sat out the 1930 season over a salary dispute.
Roush finished his 18-year career with a .323 lifetime average, 268 stolen bases and 182 triples. He never struck out more than 25 times in a season and had 30 inside-the-park home runs.
Roush, who used a massive 48-ounce Louisville Slugger (the heaviest bat used in baseball), claims that he never broke a bat in his big league career.