What happened to the run defense?

DETROIT -- A month ago, the Green Bay Packers were playing the run like they did in 2009, when they led the NFL in rushing defense.

And they were on a record-setting pace.

Through the first six games of the season, they had allowed an average of just 79.0 rushing yards per game. They were on track to better their team-record mark of 83.3 rushing yards allowed per game from that 2009 season.

And then they hit the meat of their schedule.

Two games against Adrian Peterson and one each against Matt Forte and LeSean McCoy slapped the Packers back into reality. Either their run defense wasn’t as good as they thought or they crumbled at the sight of some of the league’s top running backs.

Whatever the reason, the Packers went from third in the NFL in rushing defense all the way to 19th after a five-game stretch in which they allowed 796 yards rushing -- an average of 159.2 per game. In the first six games, they yielded just 474 yards on the ground.

Fixing the run defense might be priority No. 1 for defensive coordinator Dom Capers heading into the Thanksgiving game at the Detroit Lions.

“We were playing the same defense,” Capers said. “We were just playing it better. That’s the way this thing goes. It’s a fine line in this league in terms of whether you’re on point or if you just miss him a little bit things start to roll downhill on you. That’s no excuse. We have to play better run defense.”

In McCoy, Peterson and Forte, the Packers played the Nos. 1, 2 and 5 rushers, respectively, in the NFC.

It doesn’t get much easier on Thursday, when they must face the Lions’ Reggie Bush. While Bush ranks only eighth in the NFC in rushing yards, his average per carry (4.6 yards) is higher than both Peterson (4.4) and Forte (4.5) and only fractionally less than McCoy (4.7).

When last they played the Lions in Week 5 at Lambeau Field, they held Bush to just 44 yards on 13 carries. But on that day, the Lions played without leading receiver Calvin Johnson, who was out with a knee injury, and they never led in the game, forcing them to abandon the run.

“You can give credit to good backs; we’ve played some good backs the last couple weeks,” Packers defensive tackle Ryan Pickett said. “We’ve got to give them credit. We’ve just got to get back to the basic fundamentals. … When you get the opportunity, you’ve got to make a play. We had a lot of missed tackles, and we had some missed assignments. We’ve just got to get rid of that.”

According to ProFootballFocus.com, the Packers have missed an average of 9.2 tackles per game in their last five games. In the first six games, they missed only 6.8 tackles per game. Not all of those have come against the run, but it illustrates Pickett’s point.

The Packers missed 11 tackles -- their second-highest total of the season -- in the 26-26 tie against Minnesota on Sunday, when they allowed a season-high 232 yards rushing. To be sure, they played a full extra quarter of overtime. Throw out the overtime stats, and the Packers still would have allowed their second-most rushing yards of the game.

“It’s like I said after the last week, usually it has to do with missed tackles and technique issues as well as not fitting in your gap,” Packers linebacker Clay Matthews said. “Obviously it’s easier said than done, but we just need to get back to that. Obviously it makes it a little more difficult when you’re playing from behind, but that once again goes on the defense for giving up too many points. Hopefully we can put some points on the board and get them in an advantageous position and get after the quarterback and get back to what we do, which is creating turnovers.”