Cardinals of the Midwest League, and the Single-A St. Petersburg Cardinals of the Florida State League. Herndon spent the full 1973 season with the St. Petersburg Cardinals. Appearing in 141 games, he compiled a .287 batting average (.343 on-base percentage) and stole 41 bases. Herndon began the 1974 season with the Arkansas Travelers of the Texas League. He appeared in 132 games, compiled a .285 batting average, and stole 50 bases. He was called up to the Cardinals in September 1974. He appeared in at least 10 games as a pinch-runner and one as a late-inning replacement. The Cardinals were reportedly grooming Herndon as a replacement for Lou Brock. In his only plate appearance, he hit a single. Used principally as a pinch-runner, he also scored three runs. Herndon began the 1975 season with the Tulsa Oilers, the Cardinals Triple-A team in the American Association. San Francisco Giants On May 9, 1975, the Cardinals traded Herndon and minor-league pitcher Tony Gonzalez to the San Francisco Giants in exchange for pitcher Ron Bryant. Herndon spent the remainder of the 1975 season with the Phoenix Giants, San Francisco's Triple-A club in the Pacific Coast League. He appeared in 115 games with Phoenix in 1975, batting .269 with 17 stolen bases. Herndon began the 1976 season in Phoenix but was quickly called up. He became the Giants' starting center fielder in 1976, appearing in 115 games, 110 of them in center field. He compiled a .288 batting average as a rookie (.337 on-base percentage) with 42 runs scored, 16 extra-base hits and 12 stolen bases. Defensively, his performance was mixed. He ranked fifth among National League outfielders with eight errors, but he also ranked third with four double plays turned. At the end of the season, The Sporting News selected Herndon for its National League Rookie of the Year award. The publication credited Herndon's "tremendous throwing arm, excellent speed and defensive maturity not often found in a first year man." Herndon injured his leg playing winter ball after the 1976 season. He reinjured the leg in June 1977 and underwent knee surgery to repair the damage. He appeared in only 49 games during the 1977 season, and his batting average dropped to .239. By late August 1977, Herndon claimed he was healthy and ready to play, but the team refused to activate him. Herndon checked out of the team's hotel and did not