By Alek Arend Longtime NFL assistant coach and former Detroit Lions head coach Rod Marinelli has finally called it a career. Marinelli is planning to retire, per NFL insider Ian Rapoport. The longtime coach is 72 years and read to move on. “Former #Lions head coach and most recently #Raiders DL coach Rod Marinelli is planning to retire, sources say,” Rapoport wrote on Twitter. “He’s had interest in continuing to coach, but has packed up and headed to Texas. At 72, Marinelli has been one of the game’s most respected teachers.” “Great coach. Enjoy your retirement, you earned it,” one fan wrote. …