The Packers improved to 1-1 with their 23-10 win over the Bears. The main source behind the win came from an unexpected unit: the defense.

For the second game in a row, Green Bay’s vaunted passing attack looked out of sorts. On the other hand, the defense, which gave up the most yards in the NFL last season, dominated Chicago and looked as good as it has since the Super Bowl run two years ago.

The defensive improvement is encouraging, but the struggles on offense are disconcerting for a team that shattered franchise records in 2011.

Here is the Packers’ Week 2 report card.

Offense: C. QB Aaron Rodgers and this offense were nearly unstoppable last season, which is why expectations were sky-high entering 2012. They have not reached those expectations so far. Through two games, Rodgers’ passer rating is 89.9, more than 30 points lower than last year when he set the NFL record with a 122.5 rating. He’s thrown two interceptions, one-third the total he threw all of last season. Rodgers is averaging 6.9 yards per attempt, down from 9.2 in 2011. And finally, the worst stat of all, the offense has scored just twice.

It’s possible teams have simply figured out a way to defend the Packers. The Bears, like the 49ers the week before, played a two-deep shell with their safeties back, taking away the big play and forcing the Packers to move the ball underneath and on the ground. Green Bay isn’t incapable of playing that way, but it isn’t their preference. The rushing attack looked much better -- RB Cedric Benson gained 81 yards on 20 carries, providing some semblance of offensive balance. But Rodgers missed some throws and receivers dropped key passes. Statistics aside, the offense isn’t passing the eyeball test -- they look different, discordant, and the result is they are not playing to their potential.

Defense: A. It was a complete and dominant effort against the Bears. The Packers ransacked the Bears up front and abused QB Jay Cutler, sacking him seven times on 12 hits. OLB Clay Matthews recorded 3.5 sacks, giving him six in two games, the same total he had all of last season. The pass rush looked better than it has since the 2010 season. The pressure paid off, resulting in four interceptions. Two picks came courtesy of CB Tramon Williams, who shut down Bears WR Brandon Marshall, limiting him to just two catches for 24 yards. The Bears other big target, rookie Alshon Jeffery, was blanketed by new starter Sam Shields, who held Jeffery to one catch for seven yards.

The improved play could be attributed to the coaching staff shaking up the defensive rotation. After allowing 30 points to the 49ers in Week 1, Shields started for Jarrett Bush at right cornerback; rookie Jerron McMillian took M.D. Jennings’ place as the nickel safety; second-round CB Casey Hayward was used in the dime package. Up front, defensive linemen Jerel Worthy and Mike Daniels each recorded a sack and young talent like first round pick LB Nick Perry and undrafted rookie OLB Dezman Moses took advantage of their opportunity to play with solid performances. In the end, the new blood infused youth and talent into a defense that finally looked formidable.

Special teams:  A. The highlight of the season so far was the Packers’ fake field goal touchdown against the Bears. With less than two minutes remaining in the first half and his offense unable to get anything going, coach Mike McCarthy called for the fake on 4-and-26 from the 27-yard line. It was a touchdown or bust play that numerous players afterward said was a “gutsy” call. Holder Tim Masthay caught the snap, flipped it to TE Tom Crabtree, who followed some key blocks for the game’s first touchdown and a 10-0 Packers' lead.

K Mason Crosby converted all three of his attempts, including a 54-yarder. WR Randall Cobb had a nice, 16-yard punt return that resulted in one of Crosby’s field goals in the fourth quarter. And Masthay continued to impress, slamming five punts an average of 47.6 yards, including a long of 57. He landed three punts inside the 20-yard line.

Coaching: A-. McCarthy’s decision to try the fake field goal at the end of the first half, with his offense sputtering, was the perfect call at the perfect time. It caught the Bears completely off guard, was flawlessly executed and was a crucial shot in the arm before halftime. Defensive coordinator Dom Capers shook up the defense, handing huge roles to rookies and it paid off. The scheme, which coaches have consistently defended even during last year’s debacle, finally seems to have the personnel to be successful.

After Week 1, when questions floated around that McCarthy was outcoached, his team looked focused and prepared against the Bears. The defense and special teams were superb, the tackling fundamentals looked refined and the Packers committed just four penalties. The offense, though, needs to be tinkered with soon. The coaches and players are loath to use the term “blueprint,” but opponents will continue to sit back with their safeties deep, taking away the big play and forcing the Packers to run the ball and move the chains underneath. That will be the formula until Green Bay shows it can beat that defensive scheme.

Follow Packers reporter James Carlton on Twitter: @CBSPackers and @jimmycarlton88.