Detroit Lions WR Marvin Jones focused on strengthening his lower body to improve his explosiveness this offseason. He worked out with former NFL WR Randy Moss to help him in that endeavor and to improve his yards after the catch. Head coach Jim Caldwell praised Jones for the offseason he has put together so far. ‘This guy is right there on the verge of maintaining that kind of explosive start that he had last year,’ Caldwell said. ‘He’s really, really had a real good spring.’