Kores played the majority of his career in the minor leagues with the Des Moines Boosters (1911–1912), Portland Beavers (1913–1914), Rochester Hustlers (1915), Nashville Volunteers (1916–1917), Louisville Colonels (1918), Toledo Mud Hens (1920), and Indianapolis Indians (1920).

In the minors, he compiled a career .274 batting average with 1,225 hits, 212 doubles, 91 triples, and 29 home runs in 1,243 games played.

[2] Kores spent his first full professional season with the Des Moines Boosters of the Class-A Western League in 1911.

After the season, Des Moines general manager Jack Holland attempted to trade Kores to another team, but no organization showed interest.

[2] The day before the Des Moines Boosters opening series of the 1912 season, Kores signed a new contract with the team.

[3] With Des Moines that year, he batted .298 with 182 hits, 25 doubles, 10 triples, and 10 home runs in 162 games played.

At the end of the 1912 season, the Portland Beavers of the Double-A Pacific Coast League drafted Kores from the Boosters.

[10] In September, 1914, the New York Giants drafted Kores from the Portland Beavers in what the Oakland Tribune a "secret lottery".

[11] Kores rejected the Giants contract offer, stating that he could make as much money in the Pacific Coast League then he could in the majors.

[14] Before the 1915 season, it was reported that the St. Louis Terriers of the Federal League were interested in Kores, whose contract was owned by the New York Giants.

On July 23, it was reported that Kores had left the Hustlers to join the Major League St. Louis Terriers.

[17] Officials from the Hustlers said that it did not come as a surprise that Kores had left the team, because he was in talks with the St. Louis club for months.

[19] Before the start of the 1918 season, Kores was sold from the Nashville Volunteers to the Louisville Colonels of the Double-A American Association.