Born in Atlanta, Hearn attended Georgia Tech and signed with the St. Louis Cardinals in 1942. He spent two years in the minor leagues and three performing military service in the United States Army during World War II, before being called up in 1947. After compiling a 21–17 record for the Cardinals over all or parts of four seasons, he was placed on waivers and claimed by the New York Giants on July 10, 1950. He then went on to lead the National League in earned run average and win 11 of 14 decisions for manager Leo Durocher that season. Hearn was a crucial member of the Giants' starting rotation, winning 17 games and helping them overcome a 13-game mid-August deficit to the Brooklyn Dodgers to win the NL pennant. He defeated the Dodgers 3–1 in Game 1 of the NL pennant playoff, and pitched effectively in the 1951 World Series, defeating the eventual champion New York Yankees 6–2 in his only start, in Game 3 at the Polo Grounds. He gave up only one earned run in the Series, for a Fall Classic ERA of 1.04. Hearn pitched in New York for five more seasons, but compiled only a 50–54 record through 1956. The following season he was traded to the Philadelphia Phillies, where he had some success as a relief pitcher. During his last season, Hearn was involved in a bizarre episode. On May 10, he pitched 1 innings against the Pittsburgh Pirates and gave up two runs before the game was suspended. He was given his unconditional release 12 days later. The suspended game was resumed in July, and Pittsburgh held on to win. Thus Hearn was charged with a loss, weeks after his career had ended.
Statistics
Hearn he hit two inside-the-park home runs in his career, including one in a game on July 9, 1955, in which he also hit a traditional fence-clearing homer. Hearn's feat is notable in that there have been only a total of eight inside-the-park home runs hit by pitchers since 1954. Overall, Hearn appeared in 396 games, winning 109, losing 89, with an ERA of 3.81, 63 complete games, ten shutouts and eight saves. In 1,703 innings pitched, he allowed 1,661 hits and 655 bases on balls, with 669 strikeouts. He was an excellent golfer and opened a golf school after his baseball career ended. He died at age 77 in Boca Grande, Florida.