Horner was born in Junction City, Kansas, but grew up in Glendale, Arizona, attending Apollo High School where he set school records. His college career at Arizona State University culminated with being named the first winner of the Golden Spikes Award. With his nine home runs in 1976 he is tied with Ike Davis for third all-time by a Sun Devil freshman, two behind Barry Bonds. A second baseman for TSN's College All-America team in 1977 and 1978, Horner set a then-NCAA record of 58 career home runs for Arizona State, set a 25-homer single-season record, and was selected the MVP of 1977 College World Series. Horner was drafted by Atlanta with the first overall pick in the 1978 amateur draft, and he made his Major League Baseball debut the same year. He is one of only a handful of players to go directly from college to the starting lineup in the majors without spending a day in the minor leagues. In his first game, he belted a home run off future Hall of Fame pitcher Bert Blyleven of the Pirates. In 89 games, Horner batted.266 with 23 home runs and 63 runs batted in in 323 at-bats, with an on-base percentage of.313 and a slugging percentage of.539. His 23 home runs led all National Leaguethird basemen in 1978. He won the National League Rookie of the Year honor over Ozzie Smith. In 1979, Horner batted.314 with 33 homers and 98 RBI. In 1980, Horner batted.268, 35 HR, 89 RBI despite being sidelined for 79 games in both seasons after recurring shoulder and leg injuries. In the strike-shortened 1981 season, he hit.277, 15 HR, 42 RBI in 79 games. Horner enjoyed his best statistical season in 1982, finishing with 32 home runs, 97 RBI, and an OBP of.350, while slugging.501. In August 1983, Horner was hitting.303 with 20 homers and a career-high OBP of.383 when he fractured his right wrist while sliding, missing the last 43 games of the season. In May 1984, Horner broke his left wrist while diving after a ball and he was sidelined for the rest of the season. In 1985, Horner played 130 games and finished with a.267 BA, 27 HR, and 89 RBI. In 1986, Horner set personal highlights. On July 6, 1986, in a game against the Expos, he became the eleventh player in Major League Baseball history to hit four home runs in a single game and only the second one to do so in a game that his team lost. Later in the season, after hitting a record 210 career home runs without a grand slam, Horner finally belted a homer with the bases loaded to give the Braves a 4–2 victory over the Pirates. Horner's record for homers without a grand slam stood until 1998 when Sammy Sosa surpassed the mark by hitting his first grand slam on the 248th home run of his career. Horner became a free agent in 1987, after his first season of more than 500 at bats. Although Horner was still near his peak, the Major League clubs were then colluding to drive down salaries, so no offers were made to Horner, who consequently signed a one-year contract with the Yakult Swallows of the Japanese League. He hit 31 homers and had 73 RBIs for the team. He was given number 50 by the organization because that was the number of home runs they expected him to hit. In 2004, Horner would receive more than $7 million from the successful lawsuit the players filed against the owners and their illegal collusion. Horner returned to the majors in 1988 with the St. Louis Cardinals, but after 60 games, he injured his left shoulder. After being invited to spring training by the Baltimore Orioles in 1989, Horner announced his retirement. In his ten-year Major League career, Horner batted.277 with 218 home runs, 685 RBIs, 560 runs, 1,047 hits, 169 doubles, 8 triples, 14 stolen bases, a.340 on-base percentage, and a.499 slugging average in 1,020 games. Defensively, in 684 games at third base, he compiled a.946 fielding percentage, and in 330 games at first base, he posted a.994 fielding percentage. Overall, his career fielding percentage was.977. On July 4, 2006, Horner was inducted into the College Baseball Hall of Fame as a member of its inaugural class.
