Glasscock was one of the National League‘s premier 19th-century shortstops. He was called “Pebbly Jack” for his habit of groundskeeping at his position, picking up and tossing away pebbles, which some baseball historians claim were imaginary. He played bare-handed, was one of the first to use a signal to inform his catcher which middle infielder would cover second on a steal, and was one of the first shortstops to back up throws to the second baseman. He managed Indianapolis for part of 1889, while leading the NL with 205 hits, and discovered 18-year-old farmboy Amos Rusie in the nearby countryside. In 1890 he replaced shortstop Monte Ward on the Giants when Ward led the defection of talent to the Players’ League. Glasscock won the NL batting title that year, hitting .336, and had six singles in six at-bats on September 27. He topped the .300 mark five times.