Leonard grew up in Wortham, Texas. He is the only child of L.A. and Sammie Lee Davis, but has 21 half-brothers and half-sisters. He attended Wortham High School, where he led his Bulldogs basketball team to the state championship in 1997. In football, he received All-American honors playing defense and offense for a school with fewer than 150 students. He also lettered in track.
College career
Davis received an athletic scholarship to attend the University of Texas at Austin, arriving in John Mackovic's final season, with the intention of playing at defensive tackle and even starting three games. He was moved to the offensive line after Mack Brown was named the new head coach. He played left tackle in his last two years. During his career, he blocked for Heisman Trophy winner Ricky Williams and Hodges Mitchell. Following his senior season in 2000, he was a first-team All-Big 12 selection, and was recognized as a consensus first-team All-American. He was also a finalist for the Outland Trophy in two separate occasions.
Professional career
Arizona Cardinals
Davis was selected second overall in the 2001 NFL Draft by the Arizona Cardinals, and was named the starter at right guard as a rookie. The next year injuries on the offensive line forced the team to move him to right tackle. He was moved back to guard in 2003. In 2004, after Dennis Green was named the new head coach, he was moved to left tackle where he would remain for three seasons, even though he struggled at the position and was one of the highest penalized players in the league. On February 17, 2007, the Cardinals told Davis that they would not name him a franchise or transition player, clearing him to become an unrestricted free agent.
Dallas Cowboys
On March 4, 2007, Davis signed with the Dallas Cowboys for a seven-year, $49.6 million contract with $18.75 million guaranteed, who were looking to replace the retired Marco Rivera. At the time, the contract was criticized in the media, for the amount of salary cap space being assigned to a player that would play guard and that had an average performance in previous years. According to Forbes, Davis was the highest-paid NFL player and 19th overall athlete in the 12-month period ending in June 2007, earning $25.4 million. He was named the starter at right guard and would flourish in Dallas by going to the Pro Bowl in his first three seasons. He had an exceptional year in 2007, as he received Pro Bowl and All-Pro honors for the first time in his career. The Cowboys finished 13-3 and won the NFC East division, but suffered a disappointing first round playoff loss against the New York Giants. In 2009, the Cowboys again won the division and also their first playoff game in 13 seasons. He was released on July 28, 2011, due to declining play and the team's lack of salary cap room.
Detroit Lions
On November 7, 2011, he signed a one-year deal with the Detroit Lions. After joining the team midway through the season, he was declared inactive for every game with the Lions.
On July 26, 2012, Davis signed a one-year deal with the San Francisco 49ers as a free agent. He was a backup and was a part of the team that reached Super Bowl XLVII. In the game, he contributed on special teams, but the 49ers fell to the Baltimore Ravens by a score of 34–31.
