No. 7: Byron Scott
Byron Scott is a name well-known to Los Angeles Lakers fans as he joined the team as a rookie in 1983 and was a key member of the rotation of the Showtime Lakers, winning three titles alongside Magic Johnson, Kareem Abdul-Jabbar, James Worthy and Michael Cooper.
In 1998 when he retired from playing basketball he began his coaching career as an assistant coach in Sacramento, and less than two years later was hired the head coaching job for the New Jersey Nets. Scott led the Nets to the NBA Finals two times, then had two disappointing tenures in New Orleans and Cleveland.
In 2014 Scott's connection to the Lakers brought him into consideration for their open head coaching position and he was hired to lead a team rebuilding in the aftermath of the failed Dwight Howard - Steve Nash additions. The Lakers won just 21 games his first season, then a franchise-worst 17 in 2015-16, which was Kobe Bryant's final season in the league.
Scott was obviously not dealt a great hand when he took over a rebuilding team, but he took a bad hand and did nothing with it. The Lakers had a lot of young talent on those teams, players that would go on to have long careers elsewhere in the league, and Scott got essentially nothing out of them.
Of all head coaches in franchise history to coach for at least two seasons, Scott had the worst winning percentage of any of them. When you're bad elsewhere, bad with the Lakers and then don't get another head coaching job, it's pretty clear you're just a genuinely bad head coach.