At age 19 he played for teams in Fort Worth, Texas and Guthrie, Oklahoma before joining the Philadelphia Giants.

In 1910, his only full season with Philadelphia, Santop and fellow rookie Dick Redding formed a "kid battery", catcher and pitcher.

For example, Santop was the recipient of a knockdown pitch from ex-New York Giant Jeff Tesreau in an exhibition game.

[12] However, one month later, one newspaper reported that doctors at Camp Dix examined him and "found he had a broken and badly twisted arm."

[4] After the war, Santop was the league's biggest drawing card[14] and received $500 a month, one of the highest salaries paid, playing for the Hilldale Daisies.

[16] Hilldale won pennants from 1923 to 1925, but an error in the 1924 Colored World Series basically ended Santop's Negro League career.

With Hilldale leading a game 2–1 in the bottom of the ninth with one out and the winning runs on base, Santop dropped a popup off the bat of Monarchs catcher Frank Duncan that would have been the second out.