Before the 2009 NFL season, the Green Bay Packers ran a 4-3 defensive scheme. But that changed when then-head coach Mike McCarthy hired Dom Capers as his new defensive coordinator. Capers brought with him a 3-4 defensive scheme. That scheme, or at least a form of it, continued to be run after Capers departed in 2017. Mike Pettine and Joe Barry both ran a form of a 3-4 defense. But now, with the arrival of new defensive coordinator Jeff Hafley, the 3-4 departs, and the 4-3 enters. The new scheme means that the Green Bay Packers defensive line will have some learning to do in this year’s training camp.