Smith was born in Mobile, Alabama, the second of Clovi and Marvella Smith's six children (five boys and one girl). While the family lived in Mobile, his father worked as a sandblaster at Brookley Air Force Base. When Smith was six his family moved to the Watts section of Los Angeles. His father became a delivery truck driver for Safeway stores, while his mother became an aide at a nursing home.

In 1985, Smith amassed a .276 batting average, 31 stolen bases, and 591 assists in the field. The Cardinals as a team won 101 games during the season and earned another postseason berth. Facing the Los Angeles Dodgers in the now best-of-seven NLCS, a split of the first four games set the stage for Game 5 at Busch Stadium. With the score tied at two runs apiece in the bottom of the ninth inning, Dodgers manager Tommy Lasorda called upon closer Tom Niedenfuer to pitch. Smith batted left-handed against Niedenfuer with one out. Smith, who had never hit a home run in his previous 3,009 left-handed major league at-bats, pulled an inside fastball down the right-field line for a walk-off home run, ending Game 5 in a 3-2 Cardinals victory. Smith said, "I was trying to get an extra-base hit and get into scoring position. Fortunately, I was able to get the ball up." The home run not only prompted broadcaster Jack Buck's "Go crazy folks" play-by-play call, but was also later voted the greatest moment in Busch Stadium history by Cardinals fans.  After Smith's teammate Jack Clark hit a late-inning home run of his own in Game 6 to defeat the Dodgers, the Cardinals moved on to face the Kansas City Royals in the 1985 World Series. Once again sportswriters were quick to draw attention to Smith's outstanding defensive play instead of his 2 for 23 effort at the plate. After the Cardinals took a three-games-to-two advantage, a controversial Game 6 call by umpire Don Denkinger overshadowed the remainder of the Series (which the Royals won in seven games).  What was not publicly known during the regular season and playoffs was that Smith had torn his rotator cuff after suffering an impingement in his right shoulder during the July 11-14 homestand against the Padres. After suffering the impingement diving back into first base on a pickoff throw, Smith altered his throwing motion to such a degree that the rotator cuff tear subsequently developed. The 5'10" (1.78 m), 180-pound (82 kg) Smith opted to forgo surgery and instead built up his arm strength via weightlifting, playing through whatever pain he encountered. Said Smith, "I didn't tell anybody about the injury, because I wanted to keep playing and didn't want anybody thinking they could run on me or take advantage of the injury. I tried to do almost everything, except throw a baseball, left-handed: opening a door, turning on the radio--everything. It didn't get any better, but it was good enough that I didn't have to have surgery."  Because of his injury, Smith let his then four-year-old son Nikko perform his traditional Opening Day backflip before the Cardinals' first home game of the 1986 season. Smith made an "eye-popping" play later that season on August 5, during a game against the Philadelphia Phillies at Busch Stadium. In the top of the ninth inning, Phillies first baseman Von Hayes hit a short fly ball to left field, which was pursued by both Smith and left fielder Curt Ford. Running with his back to home plate, Smith dove forward, simultaneously catching the ball while parallel to the ground and flying over the diving Ford, avoiding a collision by inches.

Did he have any home runs?
who had never hit a home run in his previous 3,009 left-handed major league at-bats,