They thought inside the box.
At the midway point of the season, after giving up 172 yards rushing in a 44-23 loss at New Orleans, they moved Clay Matthews from outside to inside linebacker for a significant chunk of the snaps. It was a risky move with the team's best pass rusher but paid off.
The statistical impact was dramatic, with the Packers going from 32nd against the run in the first eight games (153.5 yards per game) to sixth in the last eight (86.4).
"I think if you look at the change of where we were in Week 8 and bye week into now, and obviously, statistics will show that we're moving in the right direction," Matthews, a former USC standout, said Thursday during a break from preparations for Sunday's NFC championship game at Seattle.
"Both individually and as a team, a defense really. Obviously, we're winning games and I'm making plays so as long as that's happening, we're doing something right."
Opposing teams who can't slow the run against the Seahawks don't have much of a chance for victory. Seattle is heavily reliant on bruising tailback Marshawn Lynch to both hammer a defense, and to set up passing opportunities.
When the Seahawks played host to the Packers in the Kickoff Opener, Lynch ran for 110 yards in 20 carries with a pair of touchdowns, and Seahawks defensive end Michael Bennett questioned Green Bay's desire to tackle the back at all.
"Obviously we were the more physical team today, offensively and defensively," Bennett said after that Week 1 game. "I saw supposedly some of the best players in the league not want to tackle Marshawn Lynch. Of course nobody is going to say nothing about that, but I saw a lot of guys whiff on tackles that should have been two-yard gains, and they're supposed to be the best."
The Packers had their bye week after their eighth game, and that's when they made the change, moving in Matthews and Sam Barrington, and moving out Brad Jones and A.J. Hawk. The tweak allowed Green Bay to get its 11 best defensive athletes on the field and spackle holes in the run defense.
Since 2011, Lynch ranks first in the NFL with 24 100-yard games and is the only player during that span to rush for at least 1,000 yards and 10 touchdowns each year.
"We're going to have to gang tackle," Matthews said. "We understand that he's going to make his plays; if there's one thing we have to understand is you have to get back and do it for four quarters."
By moving Matthews inside, the Packers were able to get more playing time on the outside for linebackers Nick Perry and Mike Neal. It didn't mean Matthews was exclusively inside, either, as Green Bay moves him all over, and he has 6 1/2 sacks in his last four games.
"We don't know how they're going to use him," said Seattle Coach Pete Carroll, who was Matthews' head coach at USC. "We know how they have, and anticipate some stuff, but we're going to have to wait until game time to see how they do it. But it's interesting how that coincided with their turn… Great coaching, obviously."
Carroll, meanwhile, poked a little fun at his own coaching decisions at USC when it came to Matthews and assessing his value on the field.
"When Clay came in, he was 208 pounds and he didn't run really well," he said. "He wasn't really strong but he loved playing and he tried really hard. Unfortunately, this is one of the great mistakes that I missed in my coaching at 'SC, how good of a player he was.
"Maybe his junior year somebody asked me about Clay Matthews and I said, 'I think he may be one of the better special-teamers to ever play at USC.' … It's really one of my big misses. I should have figured that out a lot sooner than I did. He made the rest of it history, and has been an extraordinary player ever since."
Neither Carroll, nor his players, will lose track of Matthews now.