By Paul Imig Special to OnMilwaukee.com Published Oct 05, 2015 at 1:56 PM

The Packers’ fast start – at least in the way Mike McCarthy defines the term – is complete. Through the first quarter of the season, Green Bay is one of six undefeated teams in the NFL and already has a firm grasp on the NFC North.

Here are the five biggest takeaways from Green Bay’s 17-3 victory over the San Francisco 49ers:

1. Defense carries Packers to a win

It’s not often that Green Bay’s defense is the biggest reason for the team earning a victory. The Packers entered Week 4 scoring an average of 32 points per game. Last season, Green Bay led the NFL in scoring at 30.4 points. With point totals like that, even when the Packers’ defense plays well, it’s usually just as a complement to a strong offensive output.

On Sunday, Green Bay’s defense held San Francisco to three points. Meanwhile, the Packers’ offense only mustered 17 points, which is its lowest total since scoring 13 points on the road in Buffalo in Week 15 last season. Unlike in that game, when the Bills scored enough for the win (21 points), Dom Capers’ group completely held the 49ers in check.

No, San Francisco doesn’t have a very good offense, scoring an average of 15 points per game in Weeks 1-3. Buffalo didn’t have an above-average offense last season, either. The difference in the two outcomes is what Green Bay’s defense was able to do against them.

2. A dose of revenge on Colin Kaepernick

The Packers played a significant role in making Kaepernick a rising star. His playoff performances against Green Bay in back-to-back seasons, beginning with the memorable 181-yard rushing game, helped make Kaepernick the talk of the NFL.

The landscape of Kaepernick’s career has dramatically shifted since then, and the Packers may have been the team that put an end to his run as even being a starting quarterback. Leading into this game, a reporter asked 49ers head coach Jim Tomsula why Kaepernick was even the starter. That was coming off of a four-interception performance by Kaepernick. Now, after finishing with a 55.4 passer rating against Green Bay – and getting notably mocked by Clay Matthews – Kaepernick might soon find himself watching from the bench.

3. Opposing RBs continue to do little damage

Carlos Hyde entered Week 4 as the NFL’s number three rusher in yards. In this game, Hyde had eight carries for 20 yards (2.5 average). That’s obviously not a lot of chances for him to get going, but the Packers also didn’t give San Francisco a lot of reasons to keep handing him the ball. The score and flow of the game played a factor, too.

After Green Bay’s poor performance Week 1 with Matt Forte (24 carries, 141 yards), the Packers have done great work against some of the league’s top running backs.

Between Marshawn Lynch (15 rushes, 41 yards), Jamaal Charles (11 rushes, 49 yards) and Hyde, that’s only a combined 110 yards on 34 carries over the past three games. The credit is due to several Packers players, but B.J. Raji and Mike Daniels have been terrific upfront while Clay Matthews has done a great job in the second level of the defense.

4. Packers rise to No. 2 in sacks category

Green Bay has 13 sacks in the past two games, bringing its season total to 17. That puts the Packers behind only the Denver Broncos (18 sacks) atop the NFL team leaderboard.

During the 2010 season that concluded with a Super Bowl victory, Green Bay finished No. 2 in sacks with 47. This season, the Packers are on pace for 68 sacks.

It hasn’t just been production from one or two players, either. Julius Peppers currently leads the team with 3.5 sacks, while Matthews and Nick Perry both have three. Mike Daniels has 2.5, Jayrone Elliott has two, and three other Green Bay players have also registered a sack. That’s a good sign that the Packers haven’t been overly reliant on one player to get to the quarterback, and it’s also an indication that the sacks could continue to come in bunches for Green Bay.

5.  Injuries seemingly catching up to the offense

Aaron Rodgers can be Michael Jordan all he wants, but even MJ needed help from a healthy supporting cast in order to look his best.

In this game, Rodgers had to get by without two of his top wide receivers (Jordy Nelson and Davante Adams), his right tackle (Bryan Bulaga), his second-string tight end (Andrew Quarless) and a not-100-percent-healthy running back (Eddie Lacy).

And it showed.

Rodgers admitted after the game that the offense didn’t click like it usually does, and it’s fair to wonder whether the Packers offense has sustained one too many injuries to be dominant. That doesn’t mean Green Bay can’t still win games in the meantime, which it proved Sunday, but the depth of the offense is certainly being tested. It might require the return of Adams or Bulaga for the Packers – at least on most weeks – to allow Rodgers to play his best.

Paul Imig Special to OnMilwaukee.com
Paul Imig spent the past five years working for FOX Sports WI. He began by covering the Milwaukee Bucks and Milwaukee Brewers before taking over the Green Bay Packers beat in 2011. In addition to his writing, Paul also made television appearances nationwide on FOX Sports 1. He can be heard on the radio statewide on The Bill Michaels Show and can be seen on Time Warner Cable's Roundtable show with Dennis Krause. Paul is the 2015 recipient of the University of Wisconsin-Milwaukee's award for Graduate Of the Last Decade (GOLD).