Which parts of the Packers' defensive personnel fit with Jeff Hafley and which need to change?

The Packers have a new vision for their defense under Jeff Hafley. That means at least part of the defensive personnel will have to change before next season.

Finding a new defensive coordinator garnered most of the attention and headlines, but the real work of rebuilding an underachieving unit had only just begun.

When the news first surfaced that the Green Bay Packers had tabbed Boston College head coach Jeff Hafley as their next DC, much remained unclear about their vision for the defense. Would the unit stay in a 3-4 base alignment with different coverages behind it or would it pivot to an even front? In either case, how much turnover would happen underneath Hafley on the coaching staff?

Most of those questions now have answers. As first reported by The Leap, the Packers will indeed transition to a 4-3 base defense under Hafley. Additionally, the coaching staff will feature extensive change on that side of the ball, the most since Matt LaFleur took over as head coach in 2019. Six of the team's defensive assistants from 2023 will not return for next season, including D-line coach Jerry Montgomery and inside-linebackers coach Kirk Olivadotti.

But while those elements of the defensive overhaul now have some clarity, the degree to which Hafley's arrival will force the Packers to remake their defensive personnel remains uncertain.

"It'll have some (influence)," Packers general manager Brian Gutekunst said of how much Hafley's hiring will affect roster decisions. "But it's not going to be like a wholesale change where we got to ship off and bring a bunch of new guys in. It's not going to be like that."

Hafley doesn't bring a particular scheme to Green Bay like his predecessor, Joe Barry, ostensibly did three years earlier. The Packers didn't chase the en vogue defensive system this time around, instead attempting to find a candidate with a diverse coaching résumé and the ability to adapt and evolve as the NFL landscape shifts.

"He's worked in a lot of different systems. He's very flexible that way," Gutekunst said of Hafley. "As he gets to know our personnel, his thoughts will kind of work more toward exactly what he wants to do."

Still, Hafley has previously worked with the San Francisco 49ers under longtime LaFleur associates Kyle Shanahan and Robert Saleh. Given how the Packers have often struggled against that particular opponent, it hardly seems unreasonable that LaFleur would desire his defense to emulate the 49ers in some form or fashion. Gutekunst suggested as much when he referred to the NFL as a "4-2-5 nickel league," an apparent nod to San Francisco.

And that necessarily means that the Packers must undergo some personnel changes to fit the new defensive plan.