From 2007 through 2009, the Packers were one of the league's top-five penalized teams all three seasons, and there seemed to be no stopping a fourth straight year in that realm.

But things have turned around. Dramatically.

On Sunday at Minnesota, the Packers were called for just one penalty for 5 yards, their fourth straight game with three or fewer penalties. Never mind that the Packers had never put together a streak like that before under Mike McCarthy. They hadn't had four games in an entire season with three or fewer flags with McCarthy as head coach.

Their total for the season is now six games with three or fewer penalties, the most by a Green Bay team since 1974 (also six). Most significantly, the Packers are 6-0 in those games.

Through 10 games this year, the Packers currently have the fifth-fewest accepted penalties in the league (53) and the third-fewest penalty yards (415) after finishing with the most and second-most in those categories last season, respectively.

So what's been the secret? If McCarthy knew that, it wouldn't have taken until his fifth season to get to this point. The one notable change was that during training camp this season, the Packers had their practice officials monitoring various technique and fundamental drills, not just the 11-on-11 full-contact team periods as had been customary. The impact of that shouldn't be discounted.

But other factors are probably at play too. The Packers are no longer the youngest team in the league, so the overall experience of the roster may have a role. Also, the 18-penalty fiasco in Chicago may have simply been the breaking point for the players, too.

The Packers had outgained the Bears by more than 100 yards (379-276), possessed the ball for 11½ minutes longer (35:49 to 24:11), had three sacks to Chicago's none and only lost the turnover battle by minus-1.

But via penalties they gave the Bears five of their 18 first downs, cost themselves four points when a touchdown was nullified and they had to kick a field goal, wiped out an interception that might have won the game in the fourth quarter, and moved the game-winning field goal from long range to a chip shot. The 152 penalty yards were the third-most in a game in team history.

"How the hell did we lose that game?" McCarthy asked rhetorically on Monday. "That was the key in that loss, because of all the productivity and the other positive plays that went on in that game.

"We just emphasize it the best we can, and our players have responded."

Since that game, the Packers have been flagged 27 times for 199 yards, an average of 3.9 penalties for 28.4 yards per game.

"You hope that all the practice pays off, you hope that all the preaching … pays off to a certain degree," offensive coordinator Joe Philbin said. "And you hope that as the year goes on you play better football."

The most impressive aspect of Sunday's one-penalty game was the venue. Minnesota's loud Metrodome is notorious for helping create false starts on offensive players who can't hear and holding calls on offensive linemen who are late off the snap.

But the Packers had none of those against the Vikings in their 31-3 win. The one penalty was a defensive offsides, and that one penalty was the fewest the Packers have ever had in the Metrodome. In fact, the last visiting team to escape the Metrodome with just one penalty was San Diego way back in 1999.

"If you can go into a game, anywhere on the road, and … when you're not hurting yourselves with penalties and turnovers and those types of things, you give yourself a chance," Philbin said.

"I guess that's the eighth time with this team (since Philbin joined the offensive staff in 2003) we've been up there and I don't recall us not having an offensive penalty like we did yesterday."

Defense on a roll
McCarthy and defensive coordinator Dom Capers pointed to an interesting stat the coaching staff analyzes in its game-to-game evaluations to illustrate how well the defense is playing right now.

The coaches chart the "win-loss efficiency" of the defense, essentially whether each play was a win for the offense or a win for the defense based on the result. McCarthy and Capers said the first time the Packers played the Vikings this year, when Minnesota rolled up 402 yards of offense and scored 24 points, the defense's win-loss percentage was its worst of the season.

On Sunday in the rematch, with Minnesota gaining just 302 yards and scoring only three points, that win-loss percentage was its highest of 2010.

"You can trace that right back to how well we played the run," Capers said. "I don't think our run statistics yesterday (17 non-QB rushes, 93 yards, 5.5 avg.) were reflective of how well we played the run. I think I charted 17 runs, and on 12 of those runs, they gained 13 yards. On five runs, they gained 80 yards."

The Packers have allowed just 10 points over their last three games to climb into a tie for the No. 1 ranking in scoring defense with NFC North rival Chicago. Both teams have given up 146 points through 10 games.

"We've got a group of guys doing a good job of communicating, and they're getting a feel for each other playing well together," Capers said. "That's what it takes to play good team defense. There's a confidence level to where guys know they can count on the guy next to him to take care of his job, his gap responsibility, and then consequently I think guys play faster."

A major factor in that No. 1 ranking in points allowed has been the red-zone defense, an area of emphasis in offseason study after the Packers ranked 28th last year in opponents' touchdown percentage once they got inside the 20-yard line (60.9 percent). After holding the Vikings to a field goal Sunday on their only red-zone trip, the Packers have allowed just 10 touchdowns in 22 opponent possessions (45.4 percent) this year.

"We've actually spent more time in red zone on both sides of the ball, training against each other in the spring and in training camp, and the dividends have definitely paid off," McCarthy said. "We're doing a great job keeping them out of the end zone, especially on the road."

The Packers have allowed just four touchdowns in five road games this season, including none in their last two (New York Jets, Minnesota).

Capers also pointed to the way the defense has responded following turnovers, not allowing a single opponent touchdown after any of the offense's 13 turnovers this season after allowing 10 TDs on the 16 turnovers last year.

"You measure how good you are on defense when you have to go on the field in tough situations, and taking pride in whatever we have to do," Capers said. "If it's on the 1-yard line, we have to find a way to keep them out. I sense that more with our team. I think we're more mentally tough this year than we were a year ago."

Injury update
McCarthy said that both safeties Atari Bigby (hamstring) and Anthony Smith (ankle) will be hard-pressed to play this week after getting hurt in Sunday's game. Jarrett Bush played a few snaps at safety on Sunday when Charlie Peprah had to come out of the game briefly, and Capers said Bush would remain the first option as a backup safety if Smith and Bigby can't play.

Receiver Donald Driver (quadriceps) and defensive end Ryan Pickett (ankle) both came out of the game no worse for wear. Both players were questionable with their injuries for the Minnesota game, but they played and didn't have any setbacks. McCarthy said their practice reps this week might be limited, but both appear on track to continue playing.

Also, center Scott Wells (arch) is going to be monitored this week as well, but McCarthy didn't make it sound as though he was in danger of missing this week's game.