Knoll made his major league debut on April 27, 1905 with the Senators and played in 79 games for them.

He committed eight errors as an outfielder in his only major league season, posting a .927 fielding percentage at that position.

[2] Knoll managed the Evansville River Rats from 1907 to 1909, leading them to a league championship in 1908.

He next managed the Ludington Mariners in 1920 and the Bay City Wolves from 1921 to 1924, leading them to successive league championships in 1923 and 1924.

He then managed the Quincy Red Birds for part of 1927 (replacing Mack Allison), the Fort Wayne Chiefs in 1928 (leading them to a league championship), the Wilkes-Barre Barons in 1929 (replacing Don Sykes) and the Fort Wayne Chiefs again in 1930.