The Saturday night game this week will feature a highly mobile yet still unproven quarterback against a very proven quarterback who’s won a Super Bowl. Hopefully it goes much better than last Saturday’s game between a highly mobile yet still unproven quarterback and a very proven quarterback who’s won a Super Bowl.

This is one the three games this weekend between teams that met during the regular season, though on one side of the ball it’s difficult to draw anything meaningful from that previous meeting, because during the 49ers’ Week 1 30-22 win over Green Bay Alex Smith was still bringing his safe-mode approach to the San Fransisco offense. Now under Colin Kaepernick, the Niners’ exotic running schemes using multiple rushers (Frank Gore, Kendall Hunter, and LaMichael James) have grown, as has the read-option offense.

The 49ers’ defense remains daunting in every aspect. But there could be a massive, painful weakness for San Fran due to a throbbing body part.

More on that in a minute. First, some numbers.

Packers offense 49ers defense
Total yards P/Game 359.4 (13th) 294.4 (3rd)
Passing yards P/Game 253.1 (9th) 200.2 (4th)
Rushing yards P/Game 106.4 (20th) 94.2 (4th)
Packers defense 49ers offense
Total yards P/Game 336.8 (11th) 361.8 (11th)
Passing yards P/Game 218.2 (11th) 206.1 (23th)
Rushing yards P/Game 118.5 (17th) 155.7 (4th)

The surface-y digits pretty much tell the tale you’d expect. This is a San Francisco defense that’s been simply dominant since Jim Harbaugh came abroad a year ago, and it’s still in the top five in three of the fundamental defensive metrics. They were also one of the few teams to intercept an Aaron Rodgers pass this year. The Packers QB threw only eight picks, and none over his last five games.

The difference between this year’s 49ers and last year’s team, though, is that under Kaepernick there’s an element that didn’t exist with Smith. That’s the running element, of course, and it’s fortified a running offense that had already achieved juggernaut status. But can the pass rush remain scary with Justin Smith playing through a triceps tear?

Thoughts and Rants

  • The Smith question is the great unknown that we’ll all repeatedly ponder right up until kickoff Saturday night. For the 49ers’ front seven, his absence went beyond just the sheer subtraction of a quality interior pass rusher who has 12.5 sacks over his last 32 games. Smith occupied blockers for the other Smith — Aldon — on the inside, freeing up space for the fast and athletic edge rusher to hurt quarterbacks. Aldon was widely considered a defensive player of the year candidate with his 19.5 sacks before Justin suffered his injury against the Patriots in Week 15. You’ll remember that game as the time the Patriots scored 21 unanswered points in the fourth quarter to tie the game, a surge that coincided with Justin’s injury. He’s been practicing, and it’s sounding like barring a last-minute setback he’ll play, but he could be a shell of himself. He was limited again today, and realistically he likely shouldn’t play, but if Robert Griffin III’s injury has taught us anything about coaches and team doctors and how they view their players’ health, it’s this: their level of shit giving is exceedingly low.
  • That Week 15 Patriots comeback still fell short, but it exposed the 49ers’ pass rush when one half of the Smiths is missing. After Aldon went through a five-game stretch that should be illegal (he had 12 sacks between weeks 10 and 14), he’s looked painfully ordinary since without his partner. He hasn’t registered a sack in three games, even though one of those games was against the Cardinals, and their 32nd-ranked offensive line that gave up 58 sacks and 97 quarterback hits.
  • Seriously, a limited Justin Smith is super serious you guys, so serious that I’m smashing this hammer home with three bullet points dedicated to his feeble limb. Grantland’s Bill Barnwell observed that prior to the near colossal collapse against the Pats, the 49ers had allowed 25 or more points in a game only once (they averaged just 17.1 points allowed per game, good for second overall with a shutout, and four games with six points or fewer allowed). So then without Smith, 21 points were posted in just one quarter.
  • The improved health of the Packers’ receivers is worrisome, but the 49ers demonstrated an ability to limit one of their versatile options: Randall Cobb. The slot receiver was targeted nine times in Week 1, one of only four games when he received nine or more targets. However, by using bracket coverage led by Parrish Cox, Cobb was limited to only 8.6 yards per catch, which is more than three yards lower than his season per game average (11.9). Cobb has since emerged and will draw more attention, and as Matt Maiocco writes, Carlos Rogers will likely shadow him this time.
  • The 49ers’ deep passing game, meanwhile, runs through Michael Crabtree, and all he’s done over his past five games is average 107.6 receiving yards (including a career high 172 yards in Week 17), score twice, and catch 35 passes on 56 targets (yep, 11.2 targets per game). Rotoworld’s Mike Clay notes that 39 percent of Kaepernick’s throws during that stretch have been directed at Crabtree.
  • But this is a different Packers team in the defensive backfield with Sam Shields and Charles Woodson healthy, and especially with the emergence of Casey Hayward. Together they contributed to an overall 76.8 passer rating for opposing quarterbacks this year, the fourth best in the league.
  • Hayward is the true standout. The second-round pick last spring is a leading candidate for defensive rookie of the year with his absurd passer rating allowed of only 27.7 on balls thrown in his direction.
  • Of course Kaepernick’s mobility is a different animal. But in Week 3 Green Bay faced the similarly mobile Russell Wilson, and he was held to a completion percentage of just 47.6 (significantly lower than his season completion rate of 64.1), with Seattle completing only two of its 11 third down attempts while Wilson rushed for 18 yards. Sure, you’ll note that all came during a rookie’s third career start, and fair enough. But for our purposes here, his legs weren’t any slower.
  • Turnovers are always key and crushing, and just writing that makes me want to hurl something at my computer screen because it’s a vicious announcer-guy cliché. But we really, seriously mean it this time, because the giveaway/takeaway differential between these two teams is nearly identical, with San Francisco at +9, and Green Bay at +7. This is where any uncertainty about Kaepernick making only his eighth career start in a playoff game comes into play. CEOs don’t have nerves, Colin. Or tattoos.