Matt LaFleur spent four seasons with Aaron Rodgers, and the Packers went 47-19 in their time together. They reached two NFC Championship Games but never a Super Bowl.
Rodgers left in a trade to the Jets but lasted only four plays with his new team before a torn left Achilles tendon ended his season.
LaFleur said he texted Rodgers after his injury.
"I feel for him," LaFleur said, via Rob Demovsky of ESPN. "Never want to see anybody go through that. Anytime you have a player of his caliber not playing football, it's bad for the game."
LaFleur tore his Achilles his first year as the Packers coach, so he knows the rehab entailed with the injury.
"I know I'm an elite physical specimen," LaFleur joked. "I would think someone of his caliber, I would bet he'd have no problem coming back from that."
Jets coach Robert Saleh said Wednesday he does not expect the four-time MVP to retire.