The person spoke Saturday on the condition of anonymity because the agreement has not been announced.
NBA rules prevent confirmation of moves until July 10, when Smith is expected to sign his deal.
The 6-foot-9, 225-pound forward scored a team-high 17.4 points last season for Atlanta and also averaged 8.4 rebounds, 4.2 assists, 1.8 blocks and 1.2 steals.
Detroit will start the 27-year-old in its front court with power forward Greg Monroe and center Andre Drummond. The Pistons fired Lawrence Frank in April, a day after they finished 29-53, and hired Maurice Cheeks in the hopes of ending the franchise’s four-year postseason drought.
HAWKS: Agreed to contracts with free-agent forwards Paul Millsap and DeMarre Carroll.
The addition of Millsap and Carroll will help make up for the loss of Josh Smith. The deals for Millsap and Carroll were struck late Friday night, after free agent Dwight Howard informed the Hawks he was going to go elsewhere. Millsap was selected by Utah in the second round of the 2006 draft. The 6-foot-8 power forward has career averages of 12.4 points, 7.0 rebounds and 1.8 assists in seven seasons in the NBA.
Although he was Utah’s longest-tenured player, Millsap’s minutes declined last season with the emergence of young players Derrick Favors and Enes Kanter – both part of a core group for the Jazz.
Carroll averaged 6.0 points and a career-high 2.8 rebounds in 16.8 minutes per game last season.
Carroll took to Twitter to thank the Jazz and their fans. “Atlanta here comes the (hashtag)JunkYardDog!” he wrote.