Early career Casey's coaching experience went back to his first coaching job at the age of 13 when Morganfield Baseball Commissioner Earl McKendree allowed the young Casey to coach a Little League team with kids just three years younger than him. He began his college coaching career in 1979 due to a suggestion made by his coach
Joe B. Hall. Casey spent a season with Hall as an assistant coach at Kentucky. The next season, Casey made the move to Western Kentucky, where he spent the next five seasons. Casey later returned to Kentucky in 1985 where he would take the role of an assistant coach and top recruiter. In late March 1988 while still serving as an assistant coach at Kentucky,
Emery Worldwide employees discovered $1,000 in cash in an envelope that was accidentally opened. The envelope was addressed to Claud Mills, the father of recruit
Chris Mills, and the sender was identified as Casey. The University of Kentucky said that the evidence collected during the investigation was inconclusive, and did not prove that Casey sent the money. The scandal resulted in Casey's resignation, and Casey was then placed on probation for 5 years by the NCAA. The NCAA later rescinded the penalty after it was shown that Casey wasn't involved in sending the package. Casey also settled outside of court in a defamation suit against Emery Worldwide. The case was originally for $6.9 million.
Overseas After his resignation from Kentucky, Casey accepted a head coaching job in the
Japanese Basketball League. During his time there, Casey coached for Sekisui Chemical and
Isuzu Motors Lynx that his teammate
Jack Givens played for. While in Japan, Casey did coaching work for the
national team alongside longtime friend
Mototaka Kohama and veteran coach
Pete Newell. During the summers, Casey continued to work with the
Japanese national team. In the summer of 1998 the team appeared in the
FIBA World Championship basketball tournament, which would be the team's first appearance there in over 30 years. At the time of his firing, the Timberwolves were 20–20, he was replaced by assistant coach
Randy Wittman, who went 12–30 for the rest of the season. During the
2008–09 NBA season, Casey served as an assistant coach for the
Dallas Mavericks. During the
2009–10 NBA season, the Mavericks won a division title. In 2011, the Mavericks defeated the
Miami Heat in the
2011 NBA Finals and won their first
championship.
LeBron James of the Heat would later admit that Casey's defensive schemes for Dallas helped make him improve his game even further after that series.
Toronto Raptors In early June 2011, the
Toronto Raptors decided not to pick up the option on
Jay Triano's contract. Casey was named the new Raptors head coach on June 21 and would run through until the 2013–14 season. Casey's first two seasons with the Raptors involved little to no success. The team exceeded expectations in the first season and underachieved in the second. The team failed to make the playoffs both seasons. During his third season with the team, it managed to set a new team record for
most wins in a season, an
Atlantic Division Championship, and its first playoff appearance in six years. On May 6, 2014, a day after being eliminated from the
playoffs, Casey and the Raptors agreed to a three-year contract extension. On November 1, 2015, Casey surpassed
Sam Mitchell's franchise record for wins, getting his 157th against
Milwaukee Bucks with the score of 106–87. On March 18, 2016, Casey became the first Raptors head coach to reach 200 wins with the franchise in a 101–94 win over the
Indiana Pacers, and twelve days later, in a 105–97 win over the Atlanta Hawks, he coached the Raptors to its first 50-win season in franchise history. On May 1, 2016, Casey coached the Raptors to their first Game 7 victory in franchise history with an 89–84 win over the Indiana Pacers in the first round of the
2016 NBA Playoffs and on May 15, he coached the Raptors to their first appearance in the
Eastern Conference finals in franchise history with a 116–89 victory over the Miami Heat in the second round of the playoffs, where they fell to the eventual NBA champions
Cleveland Cavaliers in six games. On June 7, he agreed with the Raptors to a contract extension. On January 28, 2018, Casey became the first coach in Raptors history to be selected for the
NBA All-Star Game. On February 11, 2018, he celebrated his 300th win as a coach for the Raptors. Casey's Raptors set franchise records for wins and points in the regular season as they finished first in the Eastern Conference. In the playoffs, the Raptors defeated the Washington Wizards in six games and were then swept in four games by the
Cleveland Cavaliers led by
LeBron James. Casey's conservative coaching structure and system was credited with developing the Raptors' younger players, however it did not fare well in the playoffs against the
Tyronn Lue-coached Cavaliers who were flexible rather than being consistent. On May 11, Casey was fired as the Raptors' head coach, shortly after being named as
NBCA Coach of the Year. He was named the
NBA Coach of the Year at the
2018 NBA Awards.
Detroit Pistons On June 11, 2018, Casey was named the head coach for the
Detroit Pistons, agreeing to a five-year deal. On November 14, 2018, Casey returned to
Scotiabank Arena for the first time since being fired by the Toronto Raptors, coaching the Pistons to a 106–104 win over his former team. In the playoffs, the Pistons were swept in the first round by the
Milwaukee Bucks, while Casey's former team, Raptors, won the NBA championship against the
Golden State Warriors. On May 12, 2021, the Pistons signed Casey to a contract extension through the 2024 season. On April 10, 2023, Casey stepped down as the head coach following the conclusion of
2022–23 season. During five seasons as coach for the Pistons, he led the team to a regular season record of 121–262 (.316). He transitioned to the Pistons' front office. ==Head coaching record==