Stafford: I think it will be tougher on defenses without Calvin Johnson

Calvin Johnson retired this offseason, leaving the Lions to get used to running an offense without their top receiver for most of the last decade. They signed Marvin Jones, Jeremy Kerley, Andre Caldwell and Andre Roberts as free agents to go with holdovers Golden Tate, T.J. Jones and Corey Fuller at wideout and they’ve been…