Best was placed on season-ending injured reserve in November after he couldn't shake the lingering effects from a concussion he sustained Oct. 16 against the San Francisco 49ers. Leshoure, the team's second-round pick who was expected to compliment Best, missed the entire season after tearing his Achilles' tendon during training camp.
"Both are tracking on a pace to be ready for offseason drills," Lewand said.
Despite concerns about his future after his third career concussion, Best has maintained he would "definitely" return next season.
Without Best and Leshoure, the Lions brought back Kevin Smith during the middle of the season. Smith is scheduled to become a free agent next month but said last week that he hopes to remain in Detroit. Lewand cautioned that the Lions wouldn't stop looking at options at running back.
"We can't put all of our eggs in the basket of guys coming off injury," he added.
Lewand reiterated on the call that the team's priority this offseason is to re-sign its own free agents, and he has been in contact with defensive end Cliff Avril, offensive tackle Jeff Backus, middle linebacker Stephen Tulloch and cornerback Eric Wright.