Kyle Shanahan-Brian Flores showdown should be a highlight of 49ers-Vikings rematch

Think of an optical illusion, one of those drawings with multicolored lines, that changes based on your angle. They’re wondrous shapes, created in ways that are almost impossible to understand.

Kyle Shanahan’s run game is the football version of them.

Studying the San Francisco 49ers’ ground attack is like fixating on one of these images. Is this player moving there for a reason? Or is this player moving there to make you think there is a reason? Only the artist truly knows.

Think of an optical illusion, one of those drawings with multicolored lines, that changes based on your angle. They’re wondrous shapes, created in ways that are almost impossible to understand.

Kyle Shanahan’s run game is the football version of them.

Studying the San Francisco 49ers’ ground attack is like fixating on one of these images. Is this player moving there for a reason? Or is this player moving there to make you think there is a reason? Only the artist truly knows.

What elevates Shanahan’s choreography is a combination of consistency and physicality. Offensive linemen flow to one side, and skill players drift to the other. And as they all move in harmony, they smash into opposing players with technique and force.

Call it beautiful violence. Call it disciplined aggression. Call it whatever you want. But whatever you call it, know that it’s going to lead to yards and points.

Last year, the 49ers led the NFL in rushing efficiency and explosiveness. Last week, without arguably the most important character in Shanahan’s production, Christian McCaffrey, San Francisco still ran for 180 yards and averaged nearly 5 yards per carry.

“I mean, it really doesn’t get more challenging,” Minnesota Vikings defensive coordinator Brian Flores said earlier this week.

Harrison Phillips, the Vikings’ preeminent run stopper, breathed deeply when asked to expound on the challenge.

“They don’t have tendencies,” Phillips said. “For the four plays they run one way, they’ve run four plays the other way. They go strong, they go open, they go four out, they go condensed — everything they have an answer for, so you cannot guess.”

Dissecting the illusion and diffusing the force requires a different kind of acuity, and no team displayed this better in the 2023 regular season than the Vikings. On “Monday Night Football” in Week 7, Flores’ defense limited the 49ers to zero explosive runs and their lowest yards per carry average of the season.

How did they do it? Does last year’s plan apply to 2024? And if not, what approach will the Vikings take this time around? Maintaining the momentum Minnesota has generated early this season might hinge on the answers to these questions.

Let’s start our study with a statistic: The 49ers averaged 1.53 yards after contact per rush in last year’s matchup with the Vikings, which was their lowest mark of the 2023 season, according to TruMedia.

A review of the game film shows that the Vikings, especially on early downs, used quasi-six-man fronts with three true defensive tackles: Phillips, Jonathan Bullard and Dean Lowry. They clogged interior gaps while edge rushers Danielle Hunter and D.J. Wonnum — and usually a safety like Josh Metellus or Harrison Smith — anchored the edges of the line of scrimmage.

Here is what that looked like from a first-and-10 situation in the second quarter: