Detroit Lions vs. San Francisco 49ers preview: 10 keys to victory

The Detroit Lions (13-2) are headed back to Santa Clara for a Week 17 matchup with the San Francisco 49ers (6-9) on “Monday Night Football.” If the Lions want to come away with a victory, they’ll need to execute the keys to victory laid out in this week’s Honolulu Blueprint.

49ers offensive and defensive schemes

For a detailed look at the opposing scheme, make sure you check out our complementary breakdown piece: Lions Week 17 Preview: Breaking down 49ers’ offensive and defensive schemes.

Key 1: Repeat Pin-Pull and Traps-Whams from NFCC

While the 49ers have a new defensive coordinator this season, as we discussed in our scheme breakdown (link above), their defense basically operates in the same manner it has since Kyle Shanahan took over as head coach.

“Yeah, there’s differences, there’s slight differences, but a lot of it’s the same,” Lions quarterback Jared Goff said of the 49ers scheme. “And we’re slightly different (too) and a lot of what we do is the same, so we’ll see if we change much or add some things and I’m sure they will as well. You always expect a little bit of a wrinkle when the game comes.”

One concept the Lions should repeat is the pin-and-pull blocking scheme that they deployed in last year’s NFC Championship. Here’s an excerpt from our key to victory article leading up to that playoff game:

In order to execute this concept, you need several things to be in place and the Lions have all of them. They use the proper formations, have the skill players that can execute blocks, athletic offensive linemen to pull, and speed backs to get outside quickly. With the 49ers aggressive front, you will also likely see the Lions incorporate some trap blocks from their offensive linemen (similar to pull blocks, but inside) and wham blocks from their tight ends (similar to pin blocks) in order to use the momentum from the defensive front to take them out of the play—thus opening gaps for their backs.

This blocking scheme will allow the Lions to get their rushing attack to the edges and into space where they can unleash their speed.

Key 2: Get Jahmyr Gibbs into space

With David Montgomery out for the next few weeks, the Lions will have to lean on Jahmyr Gibbs. Last week against the Bears, he played on 45 snaps and had 27 touches (23 rushing and four receptions) for 154 yards.

“I think less in the total number of carries and more about the reps,” Lions offensive coordinator Ben Johnson said of Gibbs’ performance in Week 16. “I think [assistant head coach/running backs coach] Scottie [Montgomery] said last week we were thinking somewhere in the 40 range, and we really nailed that. And so [Jermar] Jefferson and Craig [Reynolds] came in and we didn’t miss a beat when they came in and spelled him for a little bit. And then [Sione] Vaki came in for the two-minute drive and did a nice job as well. So, I would anticipate a similar rotation going forward.”

In the 49ers’ scheme, their back-seven drop into zone coverage the majority of snaps (71% of the time), leaving a light-box (80%), while also blitzing just 17.8% of the time (30th in the NFL). As a result, they leave open gaps beyond the line of scrimmage and on the edges—where speedier running backs have gashed them. For example, last week against the Dolphins, they allowed Devon Achane to run the ball 17 times for 120 yards and a touchdown while adding six catches for 70 yards receiving.

This should be a prime opportunity for Johnson to scheme up ways to get Gibbs into space where he can attack a defense that is dropping into coverage and defending the pass.

Key 3: Have Jamo attack the single-high safety

Last week against the Bears’ single-high safety looks, Jameson Williams had a career day, catching five receptions for 143 yards and a touchdown.

“That’s the potential that Jameson [Williams] has to this offense and it’s a beautiful thing to see a post versus single-high like that,” Johnson said of Williams. “I know this, it does our offense wonders going into the end of the season here and into the postseason to put that type of stuff on tape.”

As mentioned above, when the back-seven drops, they primarily shift into three coverage schemes: Cover-3 (35% of the time) and Cover-4 (20%) in zone coverage, and when they shift to man coverage, it’s almost exclusively in single-high looks (22%). That means, roughly 57% of the time, they operate with a single-high safety.

The Lions would benefit from sending Williams deep and stretching the 49ers coverage, which would further open things up for Gibbs underneath.

Key 4: Take the short passes

The goal of the 49ers’ defensive coverage scheme is to keep the play in front of them, limit offenses to make short passes, and then make a play on the ball or limit yards after catch (YAC) by being efficient with their tackling.

The good news for Detroit is, according to Next Gen Stats, the Lions have the No. 1 short passing offense in the NFL and have produced 2,383 YAC (second most in the NFL) including 449 YAC over expectation (third most). The Lions should feel comfortable taking what’s there and allowing their skill player to try and gain YAC.

Amon-Ra St. Brown shines in these situations, and on the year, he has caught 81.5% of his targets, which is the highest catch rate among receivers with at least 50 targets in the last three seasons.

If they get into third-down situations, the good news continues, because the Lions convert on third-down 46.7% of the time (fifth most in the NFL), while the 49ers’ defense is allowing teams to convert on third down 41.9% of the time (24th in the NFL). If it gets to fourth down, the Lions are converting at 69.2% of the time (fifth most), while the 49ers are allowing teams to convert 61.9% of the time (19th).

Key 5: Play-action works

One of the best weapons Goff has in his arsenal is play-action and the Lions run it 36.3% of the time, most in the NFL. When the Lions use play-action, Goff completes 73.7% of his passes (third best in the NFL), for 10.2 yards per attempt (fifth), and a 125.5 passer rating (third).

Against play-action, the 49ers' much-accomplished pass defense success rate drops from a top-10 unit down to 20th.

Key 6: Red zone execution

Red zone success has been a real asset to the Lions this season, both on offense and defense. Entering this game they’re scoring touchdowns in the red zone on 67.7% (fourth-best). On defense, they’re only allowing their opponents to score touchdowns on 50% of their trips (seventh best).

For the 49ers, their lack of red zone success has been a big obstacle to their success and has arguably led to their biggest flaw: the inability to finish. On offense, they convert 51.3% of their red zone trips into touchdowns (25th), while allowing opponents to score touchdowns on 65.3% of their red zone trips (31st).

Key 7: “Outwill” them in the run game

The 49ers run game has been hit by the injury bug... hard. They will be without their starting left tackle and left guard, as well as their direct backups. Their third left tackle (Spencer Burford) and starting right tackle Colton McKivitz are both in danger of missing this game. Additionally, starting running back Christian McCaffrey and backup Jordan Mason are both on injured reserve, and RB3, rookie Isaac Guerendo has been limited in practice after missing last week’s game—when they were forced to turn to RB4, Patrick Taylor.

But the Lions won’t let the injuries—or ineffectiveness—lull them into a sense of false confidence, as defensive coordinator Aaron Glenn believes their run game is ingrained in their mentality as an offense.

“I think it first starts off with the mentality of how they go about doing things,” Glenn said of the 49ers run game. “We know they’re going to run it, they know they’re going to run it, and their mentality is, ‘Listen, you’re going to have to stop it.’ So, it’s a tough, tough system which requires tough men, which you have to be on your assignment to be able to stop it, and we know that. And if you look at the game from last year, I thought our guys did a really good job early, and then some of their guys started to will themselves into making some plays, and that’s what we really have to do this game. Our top guys have to outwill their top guys, and I’m looking forward to seeing our guys do that.”

The Lions' run defense returned in strong form last week as they held the Bears to just 59 yards rushing, with only 23 coming from running backs. The 49ers run game operated similarly to the Bears, splitting touches between the running back, reserve back, quarterback, and wide receiver. And similarly to Chicago, they also only generated 81 yards on 18 carries last week.

The 49ers will certainly try to establish the run, it is indeed in their mentality, but if the Lions can outwill them early, they could walk away quickly.

Key 8: Continue to stack the box

With the 49ers’ run game struggling, it almost seems counter-intuitive for Detroit to stack the box on defense, but the numbers say it’s a logical strategy. When the 49ers faced a light-box this season, they had the seventh-best rushing offense in the NFL, while the Lions have one of the worst light-box run defenses in the league (29th).

Conversely, when the Lions stack the box—like they did last week vs. the Bears—they improve to the ninth-best run defense in the NFL, while the 49ers dip to 10th versus a stacked box, a much more even matchup.

Key 9: Contain and squeeze

One of the things the Lions did well last week was contain the pocket and limit Caleb Williams’ rushing attempts. They need to have the same awareness with Brock Purdy this week.

Last week, the Lions didn’t squeeze much of the pocket, an issue they’ll need to correct against Purdy. If they can’t squeeze the pocket and get pressure, Purdy has the skills to make accurate throws and extend drives. When the 49ers moved away from the run against the Dolphins in Week 16, Purdy completed 65% of his passes for 313 yards, two touchdowns, and one interception.

Key 10: Blitz

The Lions have struggled to get pressure on quarterbacks only rushing their front four and have heavily leaned on blitzing to increase their effectiveness. On the season, the Lions blitzed 35.6% of the time (third-most), but since losing Aidan Hutchinson, their blitz percentage has been 41.1% (second-most).

The 49ers have seen their opponents blitz them around 31% of the time (10th-most) but they’ve handled it well. When blitzed, Purdy produces about the same efficiency as when not blitzed and actually improves in some areas. But that was with his regular offensive line and not the cobbled-together one he will stand behind against the Lions.

So why blitz?

Because the Lions need to blitz to gain any pressure, and when Purdy is pressured, you see the drop off in his game. With the 49ers’ offensive line learning to work together on the fly, an aggressive Lions blitzing attack could lead to pressure and results. Additionally, the Lions' press man coverage holds up very well when blitzing. In fact, per Nex Gen Stats, they’re the top coverage unit in the NFL when blitzing.

So, dial those blitzes up, and let your defenders try and disrupt Purdy as much as possible.

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