In Green Bay, the galaxy revolves around Aaron Rodgers. Yet through weeks of inconsistent offensive production and melodrama, much of which could have been mitigated by a trip to Walgreens, the Packers’ much-maligned, oft-overlooked, critically understaffed defense has kept the team from falling out of the Super Bowl chase.

When the All-Pro receiver Davante Adams was out for Week 8 because of Covid-19 protocols, the Packers’ defense forced three turnovers in a 24-21 upset victory over the previously unbeaten Arizona Cardinals. When Rodgers missed Week 9 because of a positive coronavirus test, the Packers’ defense allowed just 13 points in a narrow loss to Kansas City. When the visibly rusty Rodgers returned last Sunday, the Packers’ defense pitched a shutout for a 17-0 victory over the Seattle Seahawks.

Even when their offense was at full strength in early October, the Packers won by final scores of 24-10 against the Washington Football Team and 24-14 against the Chicago Bears. Their defense now ranks third in the N.F.L. in both points and net yards allowed and sixth in total takeaways. Despite its mighty reputation, their offense ranks just 19th in points and 20th in net yards.

Most surprisingly, the Packers’ defense is carrying the team despite the absence of its two best players. The two-time Pro Bowl pass rusher Za’Darius Smith sustained a back injury in the season opener. The top cornerback, Jaire Alexander, has been out since Week 4 with a shoulder injury. Without Smith and Alexander, the Packers are not supposed to be able to pressure opposing quarterbacks or cover their opponents’ top receivers, and their defense hasn’t been able to stop the run effectively since Vince Lombardi left town.

Coordinator Joe Barry, in his first season in the role for Green Bay, deserves much of the credit for the defense’s success. Barry replaced Mike Pettine, whose quirky, Rex Ryan-inspired scheme was often scattered. Pettine sometimes rushed opposing quarterbacks with just three defenders (giving Tom Brady plenty of time in the pocket to plot his deviltry) and frequently assigned Preston Smith, a 265-pound pass rusher, to coverage duty (typically against receivers who were 60 pounds lighter and three steps faster).

Pettine’s defense forced sacks and turnovers but gave up too much easy yardage on coverage mismatches, broken tackles and simple assignment errors: It was the ideal scheme for critical failures against strong opponents.

Barry, a coaching descendant of Tony Dungy and Wade Phillips, keeps things simpler. He prefers to rush four defenders and blitzes judiciously. Barry generally keeps two safeties deep, though he slides them around at the snap to disguise the coverage. His relatively conservative approach helps eliminate both big plays and execution blunders. Opponents have completed just 23 passes of 20-plus yards against the Packers this season, the fourth-lowest total in the N.F.L., while Packers defenders have missed just 49 tackles, the fifth-lowest total in the league.

Several unheralded defenders have stepped up under Barry to fill the voids left by Smith and Alexander. Rashan Gary, a first-round draft pick in 2019, now leads the Packers with 5.5 sacks after two quiet seasons as a role player. Preston Smith, mostly liberated from coverage duties, is having a bounce-back season, and safeties Adrian Amos and Darnell Savage are thriving in more traditional roles. Chandon Sullivan, who went undrafted and was plucked from the waiver wire in 2019, is playing well in Alexander’s absence, as are Eric Stokes, a first-round pick this year, and the veteran Kenny King.

Linebacker De’Vondre Campbell, who has solidified a position that was a sore spot for years, has the most unlikely origin story of all for an All-Pro caliber defender: He played several seasons for the Atlanta Falcons.

The Packers are forced to rely on youngsters and consignment-sale free agents on defense because of the nature of their payroll. Rodgers’s compensation eats up about 15 percent of the team’s salary-cap space. The salaries of Adams, left tackle David Bakhtiari (who has been injured for much of the season) and running back Aaron Jones absorb another 18 percent or so.

There’s nothing unusual about a contender spending the bulk of its money on a franchise quarterback and his coterie — both of the Smiths also play on top-dollar contracts — but the Packers aren’t equipped to splurge for off-season reinforcements or to pursue Von Miller-types at the trade deadline. The Packers’ front office, a target of Rodgers’s ire long before his beef with the scientific community, deserves credit for filling out the back end of the depth chart with affordable contributors and ready-to-play rookies.

Alexander and Za’Darius Smith may return for the playoffs, and that won’t be a moment too soon. The Packers’ defense has a long-established reputation for playing just well enough to complement Rodgers’s heroics during the regular season, then collapsing spectacularly in a playoff defeat that leaves their quarterback murmuring his displeasure throughout the off-season. If that happens again this year, it will almost certainly be the final time. Barry will need all the help he can get to prevent history from repeating itself.

The success of the Packers’ no-name defense went largely unnoticed before Sunday’s shutout, thanks in large part to Rodgers. All Packers stories ultimately become Rodgers stories, and this one is no exception. If the Packers finally reach the Super Bowl after 10 seasons as frustrated runners-up, it will be in large part because of this midseason stretch when their defense overcame injuries, avoided mistakes and saved their superstar.