A native of Chicago, Illinois, McManus spent two years in the United States Army before beginning his professional baseball career in 1920. He played professional baseball for 22 years from 1920 to 1941, including 15 seasons in Major League Baseball, principally as a second baseman (927 games) and third baseman (725 games) for the St. Louis Browns (1920-1926), Detroit Tigers (1927-1931), Boston Red Sox (1931-1933), and Boston Braves (1934). He had four seasons in which he compiled a batting average above .300, including a .333 average in 1923 and a .320 average in 1930. He led the American League with 23 stolen bases in 1930 and with 44 doubles in 1925. In 15 major league seasons, he compiled a .289 batting average (1,926-for-6,660) with 1,008 runs scored, 401 doubles and 88 triples.