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Why we can expect Brock Purdy to bounce back against the Lions

The Lions passing defense has...struggled...to say the least

NFC Divisional Playoffs - Green Bay Packers v San Francisco 49ers Photo by Michael Zagaris/San Francisco 49ers/Getty Images

After 18 games, the real season for the San Francisco 49ers will begin on Sunday.

Anything short of any NFC Championship Game appearance would have been a failure for the 2023 version of the 49ers after consecutive appearances in the final NFC game each season.

And now, the 49ers have reached this point for a third straight season but still seek that elusive win they have yet to find since the 2019 season.

The only thing standing in front of the Lombardi-desperate 49ers? A talented Detroit Lions team in a position its franchise has yet to find itself in in the Super Bowl era.

No pressure, am I right?

These are three numbers to know before the 49ers look for its second Super Bowl appearance in four years:

14

Games. The Lions run offense had 14 games with at least 100 rushing yards and a rushing touchdown, tied for second-most such games with Baltimore.

The 49ers run stop woes continued into the postseason, allowing more than 100 rushing yards for the fourth time in the last five games after being gashed by Green Bay for 136 on 28 attempts. San Francisco faces one of the league's most consistent run games and the best duo.

Detroit featured the only pair of teammates to finish the regular season with 900 or more rushing yards each, with David Montgomery (1,015 rushing yards) and Jahmyr Gibbs (945) leading the fifth-best run game in the league. And not only can the Lions running backs hurt a defense on the ground but also in the passing game, finishing with 2,157 scrimmage yards, second-most behind Miami’s running back group and just ahead of the 49ers.

While Montgomery - in his first year with Detroit - has been established in the league for several yards now, Detroit pairing him with Gibbs gave the offense the push it needed. The rookie out of Alabama averaged 5.2 yards per attempt, fifth-best in the league and only behind Christian McCaffrey’s 5.4 average of running backs to finish with 900 or more rushing yards.

Detroit has rushed for 100 or more yards in 10 of its last 12, but the two games under the century have come in the previous three games.

69

Passes. The Lions’ pass defense allowed 69 passes of 20 or more yards in the regular season, the most in the league.

It hasn’t gotten better in the postseason for the Detroit secondary, already allowing 13 such plays in two games, twice as many as any other playoff team. The 49ers offense, on the other hand, had the most such pass plays, connecting for 75 passes for 20 or more yards.

While there’s a perception that the 49ers offense is YAC-dependent - finishing with the fourth-most YAC and highest YAC per play - it finished with the eighth-most completed air yards (2,368 - most in the Shanahan era) and tied for the most air yards per completion (7.0). It’s very much a passing offense that can beat a defense multiple ways against a defense that allowed the fifth-most passing yards this season.

Not only did Detroit’s defense allow the ninth-most YAC this year, but it allowed 3,100 completed air yards, by far the most in the league. According to Pro Football Reference, the 3,100 air yards allowed is the second-most by a defense since PFR started tracking the stat in 2017, behind only the 2021 Bengals - who just happened to go to the Super Bowl that season.

While there are some bright spots in the secondary - rookie Brian Branch and veteran C.J. Gardner-Johnson (who has only played in five games this season) - Kyle Shanahan should have a big red circle around Cameron Sutton’s name. Sutton has allowed the most passing yards (1,096), the third-most yards per reception (15.9), and the fifth-highest average depth of target (14.4) of 75 cornerbacks with a minimum of 400 coverage snaps, according to Pro Football Focus.

Sutton has already been targeted 13 times in the postseason, allowing 207 yards on nine receptions and two touchdowns. Nine of those targets were also against Mike Evans in the Divisional Round. The 49ers have plenty of options to go at the rookie cornerback, but it’ll be down to Shanahan how they attack Sutton.

12

Games. The Lions’ run defense finished with 12 games, holding the opposing offense to 100 or fewer rushing yards in the regular season, most in the league.

On the other side of the Lions’ electric run offense is a just as stout run defense. While the San Francisco offense struggled to take advantage of the Packers’ fifth-worst run defense, the Lions tout the second-best run stop in the league and haven’t allowed 100 rushing yards in a game since the beginning of December.

While the Detroit pass defense has a big play issue, the run defense only allowed 36 rushes of 10 or more yards, the third-fewest in the league, and five rushes of 20 or more yards, tied for second-fewest. Christian McCaffrey, however, finished with the most rushes of 10 or more yards (44) and third-most of 20 or more (nine).

While McCaffrey creates big runs and the Lions’ defense stops them, first downs will be the key to who wins on the ground. McCaffrey’s 5.6 yards per attempt on first down is tied with Gibbs for third-best average, while the Detroit defense allowed a league-low 3.37 rushing yards per attempt on first downs. Shanahan called a run on 276 first downs (fourth-most) compared to 204 passes (20th-most), so McCaffrey staying ahead of the chains against the tough Detroit defense will be paramount.

After the offensive struggles against Green Bay, how Shanahan chooses to split the run and pass on Sunday will be something to watch.