Harrelson grew up in California wanting to play for the Giants, who rejected him as too small. He signed with the Mets, and on September 16, 1966, stole home in the ninth to cost the Giants a key game in a pennant race they lost by one and a half games. That same week, he stole home to beat the Pirates, who finished two out. After a .108 debut in 1965, he learned to switch-hit.
Between recurring back problems and weekend duty in the National Guard Reserve, he missed considerable playing time, but when he was in the lineup, he sparked the Mets. His excellent fielding kept him in the lineup no matter what his average, but he also contributed with his speed on the basepaths and by drawing more than his share of walks. His best year was 1970, when he reached career highs in five offensive categories and tied the since-broken NL shortstop record of 54 consecutive errorless games (6/24-8/19). In 1971 he won a Gold Glove and led the Mets with 28 stolen bases. Harrelson is second on the Mets’ all-time list in games and at-bats (to Ed Kranepool) and triples, and ranks high in hits, runs, and stolen bases. He became a minor league manager and ML coach for the Mets. Pete Rose is still booed in Shea Stadium for his hard collision with Harrelson while trying to break up a double play in the 1973 New York-Cincinnati LCS. Released after 1977, Harrelson turned to softball, but was picked up by the Phillies on their way to the division title.