Many have called for the head of defensive coordinator Dom Capers (whose head ironically can’t be taken since his contract expired). However, some have argued that the problem goes deeper than just Dom Capers and really its that the 3-4 defense is inherently flawed and that the Packers should switch back to a 4-3 scheme.
This is actually a pretty interesting question: to put it another way, is the 3-4 defense something like the wildcat offense? What I mean by that is the wildcat offense took the league by storm in 2009 with the Miami Dolphins, but when the rest of the league had proper time to analyze and defend against it properly it slowly faded back into obscurity (see Tim Tebow). It could be argued that the “Blitzburgh” 3-4 defense run by both Dom Capers and Dick Lebeau took the league by storm when the Packers played the Steelers in the 2010 Super Bowl and perhaps the league has caught up and has finally figured a way to beat the 3-4 defense.