The Raptors fired Casey, 61, last month despite the team making the playoffs for five straight seasons.
Casey posted a 320-238 (.573) overall record as Raptors coach. He led Toronto to four Atlantic Division titles in five years, and three consecutive 50-win seasons.
But the franchise had its eyes on an NBA finals appearance this year after winning a franchise-record 59 games in the regular season, the second best record in the league behind only Houston.
However, Toronto fell for the third straight season to LeBron James and the Cleveland Cavaliers. It wasn’t close as the Raptors were swept in four games, prompting GM Masai Ujiri to part ways with the popular coach.
A week later, it was announced that Casey was one of three finalists for the NBA coach of the year award which will be announced later this month.
The Pistons move means that there’s only one vacant head coaching job left in the NBA — with the Raptors.
Toronto reportedly has a shortlist of two candidates — 50-year-old Nick Nurse (who has been a Raptors assistant under Casey since the 2013-14 season) and top international head coach Ettore Messina, 58, who has been a San Antonio Spurs assistant under Gregg Popovich since 2014.