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Detroit Lions vs. San Francisco 49ers preview, prediction: On Paper

A statistical breakdown, preview, and prediction for the NFC Championship game between the San Francisco 49ers and Detroit Lions.

NFL: DEC 27 49ers at Lions Photo by Robin Alam/Icon Sportswire/Corbis/Icon Sportswire via Getty Images

The Detroit Lions are a game away from their first-ever Super Bowl appearance, but a behemoth stands in their way. The San Francisco 49ers have been the favorites in the NFC all season, and it isn’t a tough argument to say they have the most complete roster in football.

That said, the Lions are here for a reason. Their 12-5 season was no fluke, and it took extremely strong efforts in the first two rounds of the 2023 NFL Playoffs for Detroit to take down two of the hottest teams in the conference.

So while the Lions are now 7.5-point underdogs to the 49ers, there certainly seems like a path for Detroit to pull off the upset. Is that actually going to happen, though? Let’s take a closer look at the matchup and offer our “objective” prediction for the game in our On Paper preview.

(If this is your first time reading “On Paper” check out our season opening preview for guidance.)

Note: As a reminder, the data in the charts is regular season only, and most stats listed in the story are for the regular season unless otherwise stated.

Lions pass offense (7th) vs. 49ers pass defense (4th)

Jared Goff has been on fire for the last month. In his last six games (including playoffs), here’s Goff’s statline:

148-of-210 (70.5%) for 1690 yards (8.0 Y/A), 12 touchdowns, 2 INTs, 109.4 passer rating

Not only is Goff enjoying one of his best-ever seasons in the NFL, but his two postseason performances were both statistically better than any playoff game he’s ever played in.

For the season, the Lions passing offense ranks fifth in adjusted net yards per pass attempt (ANY/A), fifth in passer rating (98.1), seventh in dropback EPA, fifth in success rate, and fourth in PFF grade.

The Lions do the majority of their work over the middle of the field. Per FTN Fantasy’s preview, 26 percent of Goff’s passes are over the middle of the field, lapping the rest of the league (average is 20%). That’s going to be important in a minute.

Both the Lions offensive line and Goff have done an excellent job avoiding pressure and sacks. The Lions rank 11th in PFF pass blocking grade, 13th in pass block win rate, fourth in adjusted sack rate, and fourth in sacks allowed.

There is one big problem this week, though: Kayode Awosika. The backup left guard is expected to fill in for injured Jonah Jackson this week, and while he’s only been credited with one sack allowed in five game appearances this year, he has allowed 21 pressures on just 189 pass blocking snaps. That is exactly one pressure per nine snaps. For comparison’s sake, Penei Sewell is allowing one pressure every 32 snaps. Graham Glasgow is allowing one every 16 snaps. Awosika is a big liability this week, and the 49ers have the personnel to take advantage.

The 49ers pass defense can be had, but those opportunities are few and far between. They’ve given up a passer rating of 100 or more just four times all season, and just once since November. They’ve been in lockdown mode since then.

For the season, the 49ers defense rank:

  • 6th in dropback EPA
  • 7th in success rate
  • 4th in passer rating allowed
  • 4th in ANY/A allowed
  • 3rd in PFF’s pass rush grade
  • 3rd in PFF’s coverage grade

They’re basically good at everything, and they match up particularly well against the Lions. Detroit does a ton of damage over the middle, but no team is better defending the middle of the field than San Francisco. From the previously referenced FTN Fantasy preview:

San Francisco ranks first in pass DVOA over the middle by leaps and bounds. The 49ers have a total defensive DVOA of -11.7% when opponents target the middle of the field; they were the only team in the league with a negative value there. They lead the league with just 6.2 yards per target allowed and a success rate of 41%, and are second with 10 turnovers.

That’s thanks to outstanding linebackers Fred Warner and Dre Greenlaw, who both rank in the top 15 in coverage grades among linebackers.

Additionally, while Nick Bosa gets all of the attention on the edge, the 49ers have a great interior pass rush that could give Detroit’s offensive line fits. Javon Hargrave (87.1) and Arik Armstead (86.2) both rank in the top six in PFF’s pass rushing grade. The two have combined for 12 sacks and 102 pressures on the season—insane numbers for interior defenders.

So where are the 49ers vulnerable? Although they don’t give up a ton of big plays, they are beatable on the back end. With Talanoa Hufanga out of the year, safety Logan Ryan is quite possibly their biggest weakness and outside cornerback Ambry Thomas has struggled as of late.

Player to watch: 49ers iDL vs. Awosika. Interior pressure has a serious chance of derailing Detroit’s entire operation. Goff doesn’t have the athleticism to avoid pressure straight up the middle.

Advantage: Draw. Overall, I think the Lions have the better unit, but unfortunately, the 49ers match up perfectly against Goff and company. The Lions should still be able to move the ball pretty well, but this is a highly disruptive passing defense—eighth in sacks, t-first in interceptions—so don’t be surprised if Goff turns the ball over Sunday.

Lions run offense (4th) vs. 49ers run defense (15th)

The Lions rushing attack pulled itself out of a mini-slump last week after wearing down the Buccaneers’ excellent run defense. Jahmyr Gibbs is really hitting his stride, as he’s been one of the best backs in football since Week 8. Since then, Gibbs ranks:

  • 8th in rushing yards (698)
  • 5th in yards per carry (5.3)
  • t-3rd in rushing touchdowns (9)
  • 2nd in rushing yards after contact per rush (2.8)
  • 8th in broken tackles (14)

And while both Gibbs and David Montgomery are amongst the best in creating yards after contact, they’ve both also been the beneficiary of fantastic blocking. The Lions offensive line ranks second in run blocking PFF grade, first in adjusted line yards, 13th in ESPN’s run block win rate, and ninth in rushing yards before contact.

After an extremely strong start to the season, the 49ers run defense has been just okay down the stretch. They’ve allowed at least 100 rushing yards in four of their last five games, and they’ve only held four of their last nine opponents below their yards per carry average.

While the 49ers have allowed the third-fewest rushing yards in the NFL, that is more a reflection of opportunity. They’ve faced the fewest rushing attempts in the league. Efficiency metrics highlight just how mediocre this run defense truly is. The 49ers rank:

  • 14th in yards per carry allowed (4.1)
  • 15th in DVOA
  • 26th in EPA
  • 24th in success rate
  • 29th in power success rate

In other words, the Lions should be able to control the 49ers defensive line when it comes to the run game—especially in short-yardage situations. And feeding even more into the Lions’ favorable matchup here is San Francisco’s vulnerability on the edges. Take this graphic from ESPN this week.

Player to watch: Penei Sewell vs. Nick Bosa. While Bosa is mostly known for his pass rushing skills, he’s a decent run defender, too. But if the Lions are going to attack the edges, they’re going to use the best run blocking tackle in football. Sewell’s 93.9 run blocking grade is first among all NFL offensive linemen.

Advantage: Lions +2. This is a huge matchup for Detroit and truly their only clear advantage. But it’s a big one that could lead them to victory. Not only would a successful run game help Detroit control the tempo of the entire game, but it would help keep that 49ers pass defense at bay. A balanced offensive attack with the option for play action, could be a huge help to Goff. That said, the 49ers have only given up over 150 rushing yards twice all season. Don’t expect a monster day from Detroit, but a potentially very efficient one.

49ers pass offense (1st) vs. Lions pass defense (16th)

The 49ers boast the best passing offense in football, but the chart above shows that they aren’t quite infallible. Brock Purdy has had a very boom-or-bust season. When he’s good, he’s nearly unstoppable. But when he’s bad, he’s bad.

For the season, though, the 49ers rank:

  • 1st in passer rating (110.2)
  • 1st in ANY/A (8.6)
  • 1st in yards per attempt (9.3)
  • 1st in EPA
  • 1st in success rate

Um.... they’re pretty good.

Pass protection is just okay, though. San Francisco ranks 14th in pressure percentage (19.9%), 26th in pass blocking PFF grade, and 20th in pass block win rate. Purdy mitigates some of those struggles, though, by getting rid of the ball quickly.

That said, Purdy gets a completely false reputation for being a checkdown quarterback. The 49ers rank 11th in intended air yards per pass attempt, and, individually, Purdy ranks 20th in passing attempts of 20+ yards. He doesn’t uncork it a ton, but he also isn’t afraid to.

And you can’t talk about the 49ers passing attack without mentioning all of their insane weapons. Brandon Aiyuk and Deebo Samuel are both arguably top 15 receivers in the league. George Kittle may be the best tight end in football. And don’t forget about Christian McCaffrey’s ability to catch the ball; he ranks first in yards (594) and touchdowns (7) among all running backs in the passing game.

This chart perfectly represents the Lions passing defense right now. They are just absolutely bleeding yardage on a week-to-week basis, but they’re holding opposing quarterbacks at or below their passer rating thanks to highly disruptive plays. Down-to-down, it looks pretty darn ugly. But with Detroit’s improved pass rush and opportunistic secondary, they’re hanging in these games.

Let me illustrate. In the past six games, the Lions have allowed:

  • 322 passing yards per game (most in the NFL)
  • 12 passing touchdowns (most in the NFL)

But also...

  • 19 sacks (third most)
  • 9 INTs (most in the NFL)

I would say this is some kind of unsustainable high-wire act, but this is mostly by design. The Lions know they can’t hold up in coverage, so Aaron Glenn has upped the team’s blitz percentage (fifth-highest since Week 15). That produces high-variance plays, be it explosive plays for the offense or game-shifting plays for the defense.

Player to watch: Aidan Hutchinson. The NFL’s leader in pressure just so happens to line up against the 49ers’ biggest liability on the offensive line. Right tackle Colton McKivitz has ceded the fifth most pressure in football (52) and tied for the fourth-most sacks (9).

Advantage: 49ers +3.5. This is an absolutely huge mismatch, and it likely decides the game. But let me offer two small pieces of optimism. The first comes in Detroit’s ability to pressure the quarterback. Glenn has found ways to produce unblocked defenders, and Hutchinson could very well create a dozen pressures on his own. Additionally, if the Lions catch Purdy on the right day, they could snatch a couple of turnovers. Purdy’s turnover worthy play percentage of 3.3% ranks 10th-worst in the NFL.

49ers run offense (2nd) vs. Lions run defense (1st)

The 49ers rushing attack is one of the most consistent in football. They’ve rushed for at least 100 yards in all but one game this season, and they’ve only been held below 4.0 yards per carry three times.

What’s crazy about the 49ers, though, is that they’ve faced horrible run defenses all year. All but two of their opponents are allowing a 4.2 YPC average or more, and the league average is 4.2 YPC. In other words, the 49ers have faced an above-average run defense just TWICE all season. Here’s how McCaffrey performed in those two games:

  • vs. Vikings: 15 rushes, 45 yards (3.0 YPC)
  • vs. Buccaneers: 21 rushes, 78 yards (3.7 YPC)

Still, though, McCaffrey and company have a lethal rushing attack by just about every metric. They rank:

  • 1st in EPA
  • 1st in success rate
  • 4th in yards per carry
  • t-first in rushing touchdowns
  • 6th in yards before contact per rush
  • 7th in yards after contact per rush
  • 2nd in adjusted line yards
  • 7th in power success rate

So regardless of opponent, this is still a top-10 rushing attack, almost certainly a top-five threat.

The Lions run defense has been a little more unpredictable lately, but they’ve still managed to hold opponents’ lead rusher to underwhelming yardage all season.

The Lions run defense ranks:

  • 4th in EPA
  • 8th in success rate
  • 3rd in yards per carry
  • t-23rd in rushing touchdowns
  • 6th in adjusted line yards
  • 5th in power success rate

Player to watch: McCaffrey vs. Lions LB tackling. McCaffrey leads the entire NFL in missed tackles forced and his 3.47 yards after contract rate is third in the NFL. Meanwhile, the Lions’ linebackers are all around average in missed tackle rate:

  • Jack Campbell: 7.6 (26th out of 64 LBs)
  • Alex Anzalone: 8.2 (31st)
  • Derrick Barnes: 8.2 (31st)

Advantage: Draw. This is another strength vs. strength matchup. I came into this week thinking I’d give the 49ers an advantage because of Detroit’s recent minor struggles defending the run, but upon seeing that San Francisco hasn’t faced many strong run defenses this year gives me a little more confidence in Detroit.

Last week’s prediction

On Paper notched another win last week, moving the preview to 14-5 on the season, but against the spread, I dropped to 14-3-2, expecting a closer game than we got. Still, I can’t feel too bad about my 27-23 prediction compared to the 31-23 final score. The biggest shock was Detroit’s lack of run defense, but upon looking at the snap counts, it appears the Lions were more focused on stopping the pass against the Buccaneers.

In the comment section, we got ourselves a Nostradamus. After notching a perfect prediction for the Lions vs. Rams game, commenter “Feld” did it again, predicting the exact right score of 31-23. That said, Archermq32—in the very first comment last week—also predicted the exact right score. So congrats to you both!

Your prize is a custom postcard to send to your favorite Cowboys fan:

This week’s prediction

The 49ers come out with just a +1.5 advantage over the Lions, and that advantage all comes from their passing game. That speaks to just how close the rest of this matchup is.

The good news for Detroit is that their pass defense has been outplayed for two months now, and they keep winning despite it. So there are certainly avenues in which Detroit can still win this game. If two of the following three things happen, I think they’re headed for the Super Bowl:

  • The Lions offense doesn’t turn the ball over once
  • Detroit’s running game hits at least 125 yards
  • Brock Purdy turns it over at least twice

All of those outcomes are perfectly possible. The Lions haven’t turned the ball over even once in their last three games. Detroit hit at least 125 rushing yards in 10 games this season. And they’ve forced 11 turnovers in their past six games.

But I have to go with the numbers here. Lions 24, 49ers 28.

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