SAN DIEGO -- When Ted Cottrell reviewed film of the Chargers' loss to Green Bay last Sunday, he likely needed a calculator or an abacus as an aid. Over and over, the Chargers' defensive coordinator needed to add up how many yards a missed tackle cost the defense.

"If our tackling was better, they don't get 126 yards after the catch," said Cottrell, of the shockingly high number of yards given away by shoddy tackling.

Cottrell isn't the only person irked by the poor tackling that helped Green Bay notch a 31-24 victory.

"It's something you learn in pee wee football," Pro Bowl linebacker Shawne Merriman said. "We should know how to tackle and that's something we all got on each other about after the game and during the week. It's something we will correct."

The person in charge of fixing the issue is Cottrell, a veteran of 21 NFL coaching seasons who is in his ninth season as a defensive coordinator. He was hired to replace Wade Phillips and the thinking was his familiarity with the 3-4 defense would soften the loss of Phillips, who left to be the Dallas Cowboys' head coach.

But after three games, the Chargers' defense isn't playing as well a season ago. Continuity apparently doesn't mean that an adjustment period can be avoided.

"Even if you have the same coaches with the same playbook, you still obviously have what we call 'wrinkles,' " general manager A.J. Smith said. "You can't do the same thing all the time because everybody looks at tape. So even if we had everybody still here, there would still be wrinkles in it."

A veteran like Cottrell knows this. But he also doesn't want to offer comments that make it look like he's making excuses. He simply knows the defensive unit must play better.

"There are a couple of things we're doing different but I'm not even using that," Cottrell said of any adjustment period. "We've been together since March. We've worked enough practices now.

"The idea is just make a damn play every now and then. If we knock a pass down here or make a tackle here, we're talking about how good we played."

Coach Norv Turner has a similar refrain when asked about the defense's problems. He overwhelmingly points to one issue: Tackling.

"Sometimes it looks like it's something dramatic and you have to make a million changes to get better," Turner said. "The No. 1 one thing that'll help us a great deal is to tackle better."

Improvement has to come in games. NFL teams seldom conduct contact practices during a season because the risk of injury.

"You can look like a practice all-star every day," said Merriman, "but you have to go out there and do it during the game."

Cottrell cited a few reasons for the poor tackling against the Packers.

"Sometimes it's where your eyes are and not having enough people around," Cottrell said. "And you have to see who we're tackling? You have to understand, Donald Driver, who was the main guy Sunday, is a fantastic player. I've seen him enough times when (working for) Minnesota to know about him."

The Chargers mark the fourth time Cottrell has run an NFL defense. His other stops were Buffalo (1998-2000), the New York Jets (2001-03) and Minnesota (2004-05).

Through three games this season, the Chargers are 22nd in total defense, 23rd in scoring defense and 21st in passing defense. They are ninth in defending the run.

Most alarming is the Chargers have given up 62 points with their defense on the field the last two weeks during losses to New England and Green Bay.

"What really gets under my skin and a lot of guys on the defense is seeing two teams able to march up field and move the ball," Merriman said. "That's not our defense and that's not the way we play -- missing tackles and not being as physical as we can possibly be. That's not us at all.

"We're doing everything possible in our power to change that."

Chargers notes

Kansas City coach Herman Edwards and Chargers defensive coordinator Ted Cottrell worked together with the New York Jets for three seasons and Edwards fired Cottrell as defensive coordinator after the 2003 season. Both men are playing nice this week despite overwhelming sentiment that friction remains. "We're fine," Edwards said. "Ted is obviously a great football coach and did a great job for me in New York." Cottrell broke into his trademark hearty laugh as a reporter probed for insight. "I don't want to get into that," Cottrell said. … ILB Matt Wilhelm (calf) missed practice again on Thursday and will miss his second consecutive game. … DE Luis Castillo (foot) returned to practice and should play Sunday. … WR Vincent Jackson (back) was a limited practice participant. … Chiefs RB Larry Johnson (hamstring) missed practice for the second straight day. … The Chargers released WR Carlton Brewster from the practice squad and signed WR Mark Simmons to the practice squad. Simmons was released by the Chargers on Sept. 1.

DEFENSELESS

The Chargers have struggled defensively, particularly against the pass, through the first three games under new defensive coordinator Ted Cottrell. Here is where they rank in the key defensive categories:

Rush defense: 9th (88.7 yards per game)

Pass defense: 21st (249.3)

Total defense: 22nd (338.0)

Scoring defense: 23rd (24.0 points per game)