• Bret Rumbeck

Chasing the Sun: Breaking Down Mostert's Historic Night Against the Packers

Image Credit: Stan Szeto


The last time I watched a football game with 42 rushing attempts against eight passes was probably sometime during my sophomore year of high school football. Turlock High School was not known for a stellar air attack, so grinding the chlorophyll out of the grass was our only option.

But now I can say I saw a professional football conference championship with a ratio of run to pass that was quite an anomaly.

San Francisco 49ers head coach Kyle Shanahan found every possible weakness in the Green Bay Packers’ run defense and violated it beyond all recognition. Veteran running back Raheem Mostert nearly broke a playoff record with 220 yards on the ground and four touchdowns.

Eight passes would not be much of a breakdown, so I suppose we’ll suffer through reviewing Mostert’s four touchdowns.

1st Quarter – 3rd and 8 at the GB 36 (6:01)

A constant theme in my film breakdowns this season has focused on how Shanahan’s system remains firmly grounded in old school football. His passing offense is a modern look at the West Coast Offense, while some pages of his running playbook are updated versions of power and trap runs.

What sets Shanahan aside is not how he draws up a play, but what he calls at a specific moment in the game.

Mostert’s first score was not an inside or outside zone run.

No, Gentle Reader, it was a trap run – something your high school coach probably installed during the first week of practice.

In case you forgot, a trap run tells one guard to pull to one side of the formation and block a deliberately uncovered defender. The rest of the linemen block down or move to the second level, away from the pulling guard.

Four parts of the run allowed Mostert to score from 36 yards away.

For this play, the 49ers left Packer outside linebacker Kyler Fackrell unblocked. At the snap, left tackle Joe Staley executed a surprising swim move over Fackrell to move to the second level. Fackrell was expecting to get hit but flamed out in Staley’s jet wash.

Left guard Laken Tomlinson sealed off linebacker Za’Darius Smith, who was inching his way toward the line of scrimmage.

Center Ben Garland and right tackle Mike McGlinchey double-teamed nose tackle Kenny Clark. McGlinchey quickly peeled off to hit linebacker Blake Martinez, sealing off the backside of the play.

Right guard Mike Person pulled to his left, but nearly had nothing to do on the play. Fackrell’s flat spin caused him to hit the chilly turf in a heap, which then had a domino effect. His lifeless body tripped up outside linebacker Preston Smith. All Person did was smash Fackrell into the turf, and Mostert was free to scamper off to paydirt.

2nd Quarter – 2nd and 6 at the GB 9 (9:17)

A quick disclaimer: I’m differing from a few of the other film junkies’ takes on Mostert’s second score.

The play looks like another trap, again keying on poor Fackrell. However, the motion and lead block from wide receiver Deebo Samuel gave the play more of a power look to me.

Shanahan’s power run attacks inside to off-tackle on the strong side. The lead back, in this case Samuel, is told to track the inside leg of the play side tackle and block the first defender outside the tight end. Both the tight end, tackle, and guard block down, essentially walling off the defense from the 7-hole.

The pulling guard, once again Person, comes around to pick up linebackers at the second level.

Indeed, Person did not get to the second level, and Samuel blew by the first defender outside the tight end. But, nothing is stopping Shanahan from altering a power run to beat a weak run defense.

Mostert’s speed would get him to the edge faster than his pulling guard. It made sense to have Samuel lead downfield and have Person crush Fackrell on the edge.

The Packers did not help themselves on the play. Look how far inside strong safety Adrian Amos drifted. Next, Martinez’s read steps brought him too close to the line of scrimmage to get to the edge. Once Person buried Fackrell, all Mostert had to do was follow Samuel downfield for six points.

2nd Quarter – 2nd and 9 at the GB 18 (:50)

Of course, not all of Mostert’s touchdowns could come from a powerful run attack. The 49ers were going to come away with points to close the first half of football. With under a minute left, Shanahan called “14 Man,” a split flow run play that attacks the inside hip of the play side tackle.

In 14/15 Man, the running back must square his shoulders by his third step. Further, he reads the line inside-out, starting from the center. The offensive line is using inside zone techniques play side, while the backside of the play, Kittle and Staley, block man.

Mostert helped himself on the play by pressing the line of scrimmage, moving toward McGlinchey’s inside hip, until the last second. His patience drew Campbell and Martinez to their left, clearing all space on the right side of the defense. Mostert then bent back across the grain to a wide-open gap.

Also, please send high praise to both Tomlinson and Staley for sealing off the left edge of the line of scrimmage. Tomlinson earned an 82.4 run-blocking grade from Pro Football Focus against Green Bay, his second-highest mark of the season.

The Packers single-high man coverage wasn’t helpful, even with eight players in the box.

Free safety Darnell Savage was in man coverage against Kittle, which forced him to freeze when opened up to block. I am unclear what Savage thought Kittle was going to do – possibly leak into the flat – but the handoff happened so quickly that Savage was left flat-footed.

3rd Quarter – 2nd and 10 at the GB 22 (4:56)

Mostert’s final touchdown came in the third quarter after the 49ers had run the ball 26 times against seven passes.

Shanahan called an outside zone run to the weak side, “19 Weak,” and had fullback Kyle Juszczyk lead block.

“19 Weak” is another full flow run attack to the weakside edge. The running back is aiming toward a spot outside the weakside tackle, reading the frontside combination blocks outside-in.

Juszczyk’s job is quite simple: block the Will linebacker, while the offensive line is executing outside zone blocking.

Samuel’s downfield block was what most people noticed on the highlight tape, but Garland’s immediate move to the second level could only be seen in film study.

He quickly moved to square up inside linebacker B.J. Goodson and was able to keep him away from Mostert. Pro Football Focus gave Garland a 75.9 grade against the Packers, which was his second-highest grade of 2019.

There is no way to chalk up 42 runs, 285 yards rushing and four rushing touchdowns as some kind of slight against quarterback Jimmy Garoppolo. Shanahan saw every way to embarrass the Packers’ run defense on national television and did so in a resounding way.


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