When the San Francisco 49ers and Green Bay Packers faced off in Week 1 of the 2012 NFL season, it was a game of defense above all. Despite a 30-22 score that would seem to indicate otherwise, the dominant performances for both teams came from the defensive side of the ball. Green Bay outside linebacker Clay Matthews put up 2.5 sacks on then-quarterback Alex Smith, beating left tackle Joe Staley over and over in a bravura performance.
The 49ers' defense limited the usually high-flying Packers offense to just one touchdown into the fourth quarter, and two touchdowns overall. Aaron Rodgers was sacked three times, including once by defensive end Aldon Smith, who amassed 19.5 total quarterback takedowns in the regular season. The Packers punted on six of their first seven drives, and Rodgers was the team's leading rusher with 27 yards on the ground.
It started a season in which the Packers frequently had to beat their own injuries as well as the efforts of their opponents, while the 49ers came out of the gate looking as dominant as they did in their 13-3 season in 2011. But the pack rebounded to win nine of their last 11 regular-season games with some new targets and weapons, while the 49ers started to look more vulnerable down the stretch. In two of the team's last three games, San Francisco got a narrow escape of a win versus the New England Patriots and were thoroughly dominated by the Seattle Seahawks.
That newfound mortality lined up precisely with one key injury -- the partially torn left triceps suffered by defensive lineman Justin Smith in the Week 15 turn against New England. The Patriots started a 28-point comeback after Smith was hurt in the second half, the Seahawks put up 42 points on the Smith-less defense the next week, and that vaunted defense looked all too vulnerable in the regular-season finale against an Arizona Cardinals offense that would have trouble doing much in the Canadian Football League.
To put Justin Smith's value in its rightful context, it's good to point out that Aldon Smith has all of his 19.5 sacks when Justin Smith was also on the field. In the team's last three games, Aldon Smith had no quarterback takedowns at all. Because Aldon Smith frequently uses Justin Smith as an anchor for his inside twists, and Justin Smith's double-teams give more opportunities to everyone on the 49ers' front seven, it's safe to say that if San Francisco wants to pressure Rodgers -- even against Green Bay's sub-par offensive line -- Justin Smith has best be good to go.
"God willing and the creek don't rise, he's going to play," 49ers head coach Jim Harbaugh said of Smith this week.
The Packers will throw a few new wrinkles at that 49ers defense, whether it has one Smith or two. Do-it-all receiver Randall Cobb really hit the next level in that Week 1 contest, catching nine passes on nine targets. Since then, he's become Rodgers' most versatile weapon in the passing game. Cobb will line up in the backfield, in the slot, and out wide, and defenders will have to deal with his speed from all those positions. In addition, Green Bay has a newfound consistency in its running game by way of Ryan Grant and DaJuan Harris, who gained 100 total yards in the Packers' wild-card win over the Minnesota Vikings last Saturday. Green Bay's offense is never going to be a run-first concern, but the threat of a consistent rushing attack -- which Rodgers has rarely had through his career as a starter -- will almost certainly make his offense more effective than it was in September.
The 49ers offense, of course, looks very different than it did in September. Colin Kaepernick has replaced Alex Smith at the quarterback position, giving Harbaugh more ways to befuddle defenses. Kaepernick can run the read-option and Pistol schemes as well as any quarterback in the NFL, and he's got the kind of accurate downfield arm that will frustrate opposing cornerbacks and safeties. Staley, still stinging over that Week 1 beatdown at the hads of Matthews, is eager for a rematch.
"I didn't play terrifically well the first time," Staley said this week. "I'm happy for the opportunity to play against him again -- a little redemption. When you're going against a player of his caliber, you have to be on your technique every single play, every single snap. I'm a different player now than I was Week 1."
That's for sure. Staley is now a key cog in one of the NFL's strongest and most impressive offensive lines from a fundamental perspective. No NFL team asks its linemen to do more in the running game, and the addition of Kaepernick's mobility puts more pressure on the "big uglies" when it's time to pass-block. Per Pro Football Focus' metrics, Staley gave up eight total sacks on the season, leaving him responsible for just 5.5 after that debut performance. Matthews should be similarly ready, though. After missing a month with a hamstring injury, Matthews came back to record six quarterback sacks in his last four games, including two against the Vikings last Saturday.
The inter-game battles are set, except for one -- we don't yet know whether Justin Smith will be able to hit the field at anything near full strength. And as good as the 49ers are, that one unknown could end their season if it goes the wrong way.