 In the summer after his junior year of high school, at the age of 18, Bancroft began his professional career in 1909 with the Duluth White Sox of the Class-D Minnesota – Wisconsin League. Bancroft did not have immediate success, registering a .210 batting average and .917 fielding percentage in 111 games, but he developed a positive reputation in the league. The Superior Blues acquired Bancroft at midseason, and he remained there through the 1911 season. Bancroft finished the 1911 season with a .273 batting average and 41 stolen bases, and the Blues won the league championship.
