Insider: Thumbs up to dominant defense

THE BIG PICTURE

Coach Mike McCarthy said last week this game would determine whether the Packers were off to a fast start, since four games represents the first quarter of a 16-game season. Mission accomplished. After beating the 49ers 17-3, the Packers are 4-0 for the first time since 2011 and the third time under McCarthy (2007 being the other). On Sunday, they played a complete game, with the defense dominating against longtime nemesis Colin Kaepernick (13 of 25 passes for 160 yards and one interception). Next up are home games against the Rams and Chargers, and the Packers will be heavily favored to win both and take a 6-0 record into their bye week. Little wonder why Fox-TV’s Joe Buck said during the broadcast that the Packers are “the most dangerous team in the NFL.”

TURNING POINT

John Kuhn’s first touchdown since the 2014 season opener couldn’t have come at a better time. The Packers dominated the first half but led only 7-3 at intermission. On the first drive of the second half, Aaron Rodgers used his feet on a key second-and-goal play from the 49ers 17, scampering down the sideline before being pushed out at the 1. That set up a Kuhn TD plunge for a 14-3 lead and some breathing room for the Packers. The 49ers' defense naturally was keying on Eddie Lacy, who twice had picked up first downs on fourth-and-one in the first half. Instead, the inside handoff went to Kuhn, who bulled his way into the end zone to the delight of a Packers-leaning crowd yelling “Kuuuuuhn!”

Robert's chat: When will D gets its due?

THUMBS UP

The Packers in the past had struggled mightily against Kaepernick, but this time it was a completely different story. Green Bay harassed the San Francisco quarterback all day, collecting six sacks after getting seven last week against the Chiefs. Clay Matthews spent much of the game in the 49ers’ backfield, and when he finally got a sack to end a drive in the third quarter, he celebrated by performing Kaepernick’s signature biceps kiss. “Clay was a big part of the plan and he delivered,” McCarthy said afterward. Kaepernick’s passer rating was an abysmal 55.4 as the Packers’ defense held the 49ers under 200 yards (119 passing, 77 rushing) and to only eight first downs. “Our defense played lights out,” McCarthy said. “I think it was our best performance of the year.”

THUMBS DOWN

With right tackle Bryan Bulaga (knee) still sidelined, backup Don Barclay and the rest of the offensive line had a difficult day against the 49ers’ pass rush. Rodgers was sacked by 49ers linebacker Ahmad Brooks on a third-down play at the end of the first half (setting up a missed Mason Crosby field-goal attempt) and was forced to run for his life on several occasions. In the second half, 49ers linebacker Aaron Lynch twice beat Barclay for sacks that short-circuited Packers drives. The Packers’ porous pass protection was the only thing that enabled the 49ers to keep the game from becoming a blowout.

RANTS & RAVES

RAVE: What more can you say about Aaron Rodgers? Fox-TV analyst and Hall of Fame quarterback Troy Aikman called Rodgers “as hot of a quarterback that I can ever recall seeing. The ball placement, and his vision on the field, is unsurpassed.” Rodgers (22 of 32, 224 yards, one TD, no interceptions) forced the 49ers to waste a timeout early in the second half when he nearly pulled off one of his specialties by catching their defense with 12 men on the field. On a masterful 12-play, 80-yard drive to open the game, he connected on six straight passes for 63 yards, capped by a 9-yard TD toss to tight end Richard Rodgers.

RAVE: In the two previous weeks, the Packers had held both Marshawn Lynch (41 yards on 15 carries) and Jamaal Charles (49 yards on 11) under 50 yards rushing. The 49ers’ Carlos Hyde presented another imposing challenge, and again Green Bay’s much-maligned run defense responded. The gang-tackling unit held  Hyde to only 20 yards on eight carries despite the absence of injured safety Morgan Burnett. The Packers also kept Kaepernick’s run threat in check (57 yards on 10 carries but no touchdowns on the day).

RANT: With Davante Adams sidelined by a sprained ankle, a Packers receiving corps already minus Jordy Nelson for the season again was put to the test. Rookie Ty Montgomery failed to come up with a couple of first-half passes and a 36-yard completion to James Jones was the only big play produced by the passing game before intermission. Jones (five catches for 98 yards) also had the big catch of the second half, a 38-yard reception on the drive that produced the Packers’ second touchdown. But on the whole, it was a quiet day for the pass catchers.

RAVE: Lacy practiced fully all week but concerns lingered about the sprained ankle he suffered against Seattle. His performance should put Packers fans’ minds at ease. Lacy looked just fine on two fourth-down carries that moved the chains late in the first half. On the day, Lacy had 18 carries for 90 yards (compared to nine for 28 by James Starks), an indication that Lacy’s sprained ankle isn’t bothering him too much.

Packers sack Kaepernick, 49ers for road win

DID YOU NOTICE?

» Rodgers now has not thrown an interception in 17 of his last 20 regular-season games, including the last six. The Packers won 16 of those games. With a passer rating of 99.0, however, Rodgers did fail to reach the 100 mark for the first time this season, meaning he still has done so in his first four games only once (in 2011, when he reached 100 or better in the first 12 games).

» Crosby’s miss on a 44-yard attempt at the end of the first half snapped his streak of 13 consecutive made field goals dating to last season’s playoffs.

» On their second offensive series, the Packers rolled out a no-running-back set that featured carries by Montgomery and Randall Cobb. It was an intriguing wrinkle that will give future opponents something to think about, even if it didn’t produce much (two Montgomery carries for 10 yards).

» Cobb extended his streak of regular-season games with at least one reception to 45 with a 10-yard catch in the first quarter.

» Outside linebacker Nick Perry made his case for more playing time (team-high two sacks) and Jayrone Elliott added to his “playmaker” reputation with a first-half sack on a second-and-goal play that helped force the 49ers to settle for a field goal.

» Plenty of Cheesehead-wearing Packers fans made themselves heard in a crowd of 70,799 that featured a surprising number of empty seats. A “Go, Pack, Go” chant even broke out in the fourth quarter.

» Since 1990, the Packers now are 10-2 in regular-season games played in California (vs. the 49ers, Raiders, Chargers and Rams). They are 3-1 in the Golden State under McCarthy.

— scourtney@pressgazettemedia.com and follow him on Twitter @Stucourt.