A new defensive coordinator won't fix everything when it comes to the Packers defense. Green Bay general manager Brian Gutekunst has to be ruthless when it comes to overturning the defensive roster and moving on from guys who just aren't pulling their weight.
The Packers have to surround Jordan Love with as much talent as possible, which includes a WR1, in order for him to reach his full potential. Marvin Harrison Jr. fits that bill.