He played for the Pittsburgh Pirates just at the end of the 1905 season (September 25-October 7).

The 24-year-old rookie, who stood 6 ft 1 in (1.85 m) and weighed 185 lbs., was a native of Kingston, Pennsylvania, and attended the University of Notre Dame.

Two of his famous teammates on the Pirates were future Hall of Famers Honus Wagner and Fred Clarke.

Flanagan died at the age of 66 in Wilkes-Barre, Pennsylvania.

According to SABR research, his unusual nickname was due to his speed on the bases and his large size, comparing him to a steam locomotive.