In the waning seconds of Week 3, Aaron Rodgers drove a dagger through the 49ers' secondary to secure a comeback win and expose San Francisco's vulnerable backfield. That loss sent the Niners careening towards a 2-4 record after an optimistic start, with opposing quarterbacks averaging a passer rating of nearly 110 during their losing skid.
Even after that rough patch, the 49ers have continued to struggle against elite passers and receivers, like the Bengals victory in which Joe Burrow still hooked up with Tee Higgins and Ja'Marr Chase for a combined 191 yards and two touchdowns. But 49ers defensive coordinator DeMeco Ryans has made savvy adjustments in the backfield, and with players like Emmanuel Moseley getting healthy, they may have a better shot this time around.
The key to the secondary's turnaround lies in the emergence of Ambry Thomas, a 2021 draft pick who sat out his last season at Michigan due to COVID concerns. As a result, he's grown this season in a manner you'd expect from a rookie, emerging from a rocky start to give the Niners much-needed consistency at the outside spot entering the playoffs. Early in the season, he wasn't even able to consistently find a spot on the active roster for games, sinking down on the depth chart below Josh Norman, Dontae "The Barnacle" Johnson, and 5th-round pick Deommodore Lenoir.
Since Week 14, Thomas has been a stalwart in the 49ers' secondary. That first start went about as poorly as it could have, with Thomas drawing multiple penalties, getting beat deep, and getting bailed out of another touchdown throw with a lucky penalty. But his stock has gone nearly straight up since then, culminating in his overtime interception against Matthew Stafford to send the 49ers to the playoffs.
The cumulative impact of Moseley's return and Thomas' emergence has transformed an atrocious secondary into one supporting a top-10 scoring defense. San Francisco carried a strong set of defensive games into Sunday's upset against the Cowboys, in which they held Dak Prescott to a meager 23 completions on 43 attempts and a 69.3 passer rating. With the rising performance of San Francisco's cornerbacks, much of the action turned towards the interior of their secondary. K'Waun Williams found himself targeted on a long touchdown reception, but made amends a few series later with a crucial interception. And Williams is no stranger to big games. Both he and the safety tandem of Jimmie Ward and Jaquiski Tartt played a huge role in providing a tough security net for the dominant 2019 defense, and their veteran presence is vitally important for a team that might be depleted on the defensive line.
With the Packers having shown that they're capable of slicing and dicing San Francisco's defense (Rodgers threw passes for 25, 42, and 47 yards in that Week 3 showdown), a better performance this go-around is undeniably necessary for the Niners to pull off the upset. High-impact plays in the secondary might be critical, but the Niners haven't been a massive turnover threat this year, with only nine interceptions in the regular season. Jimmie Ward's dropped interception in deep coverage against Dallas is an example of the kind of opportunity the Niners need to convert against first-team All-Pro duo Aaron Rodgers and Davante Adams to tip the scales in their favor.
Still, Niners fans can take heart that even when receivers have had big individual games against San Francisco in the past few weeks, DeMeco Ryans' unit has found ways to keep the score manageable. But now they face their biggest test. The 49ers will learn whether Thomas, who held opposing receivers to 24 yards on two catches last week, can be trusted to match up against one of the best wide receivers in the league. But if the secondary can clamp down on the Packers' secondary receiving threats, as well as create a turnover or two, San Francisco might be able to walk out of Lambeau Field with an upset. Defensive line injuries or Aaron Rodgers' right arm might cause it all to come crashing down, and San Francisco's lack of above-average secondary depth might be the death knell that ends their season.