Dissecting the 49ers' Run Game: Split Zones and Gap Schemes From Their Week 13 Loss

'Cause every hand's a winner

And every hand's a loser

And the best that you can hope for

Is to die in your sleep.

- 'The Gambler.' Don Schlitz. 1976.

Any veteran blackjack player knows when to leave the table when the deck is cold. After getting dealt a few fives or if you’re stuck splitting twos or threes, the free rail liquor drinks aren’t worth the stay, and it’s probably time to find other ways to lose money.

The 2024 San Francisco 49ers are playing with a frozen deck and stacked against them. Each week, they get dealt a 12, take a hit and then land a bust card. Unfortunately, the team cannot get up and find a new dealer.

There was little positive to wring out from the 49ers’ Week 13 drubbing by the Buffalo Bills.

On offense, left guard Ben Bartch made his first start since the 2023 season. He had a solid performance, only allowing one hurry and one pressure, and was also great in the run game.

I found myself a job when I retire: Work the backpack blower to clear the field during lake-effect snow games. Photo taken by me.

I attended the snow game in person, and while I didn’t expect a victory, I did hope for a close game. Instead, I had to be happy with a 24-ounce Labbat and a restroom line that rivaled the ones that used to exist at Candlestick Park.

Below are a few positive plays from the loss. As always, you can find more breakdowns on my X account. I can’t seem to get the clips to load properly on Blue Sky.

1st Quarter – 1 & 10 at the BUF 48 (10:27)

All those who claim head coach Kyle Shanahan doesn’t adjust and has lost playbook creativity have failed to watch the game.

Shanahan is adding a new addition to the ground attack each week, and Week 13 was no different.

On the 49ers opening possession, Shanahan called the first of many split-zone runs that resulted in a significant gain.

A split-zone run sets up like a typical inside-zone run but adds a flourish that creates a running lane. At the snap, the offensive line will move in one direction, and the back will flow the same way. But the twist is a fullback or tight end cutting against the grain to take on the end man on the line of scrimmage.

The sift movement creates a surprise cutback lane for the running back. Defenders might see this as a sleight-of-hand or a misdirection: they are reading the movement of the offensive line and often fail to cover the backside of the play.

Split-zone runs are incredibly effective against an aggressive defense that might bite quickly on the initial inside zone look.

In the play above, running back Christian McCaffrey gained 19 yards. Shanahan would return to the split zone a few more times throughout the game.

1st Quarter – 1 & 10 at the BUF 29 (9:47)

In the next play, Shanahan called in ‘F-Fly to Weak Left Clamp Y Right 17  F Stutter’, a gap run that attacks inside to off tackle on the weak side of the formation.

Bartch had an excellent block against Bills’ defensive tackle Austin Johnson, who lined up in a 2i technique.

Also, right guard Dominick Puni had a bounce-back game in Week 13. He is also improving on these pull blocks, squaring up the edge defender rather than just throwing a shoulder at him.

Thanks to these two blocks, along with fullback Kyle Juszczyk burying linebacker Matt Milano in the snow, resulted in an 11-yard gain for running back Jordan Mason.

Shanahan also opened the game with 16 Stutter, which is the same play but does not have the F block the first linebacker in the box off the ball.

2nd Quarter – 1 & 10 at the SF 23 (8:32)

Following McCaffrey’s PCL injury in the 2nd quarter, Mason took over as running back. Shanahan called in ‘North Right Clamp Joe 17 Will’ on the  next possession.

‘16/17 Will’ is a full-flow outside zone run that attacks the weak side of the formation. The running back aims just outside the tackle, where a tight end would be. Like any outside zone play, he will press that landmark as long as possible, reading the first down lineman from the outside to the inside.

By the time Mason got to his fifth step, the left side of the line was jumbled, but he looked back inside to find left tackle Colton McKivitz clearing the last defender from the lane. Take note, kids: backside blocks on outside zone runs are just as essential as those on the front side.

Mason would gain 11 yards on the play and lead the 49ers ground attack with 78 yards on 13 carriers.

The 49ers are nearing the end of a genuinely tragic season. Players and coaches have had to deal with some unique challenges, and I’m sure these issues are impacting the field.

Additionally, there’s a mathematical wave that teams ride. Teams like the Cleveland Browns or New York Jets have been on the black-hole gravity suck of depression for decades. The Detroit Lions were also on that event horizon for thousands of years but have recently found a way to eject themselves.

The ride is unpredictable and inconsistent, with the 49ers experiencing seasons in the abyss, seasons of mediocrity and a few that found themselves nearly hoisting a Lombardi Trophy. This year, the odds are not pointing to the 49ers, and no amount of great coaching or “creative” play calling will fix these odds.

Yet, I believe this roster wants to win games and finish the season strong. That starts this weekend against the Chicago Bears, and hopefully, the offense can return to fundamental football.

All images and videos courtesy of NFL.com, except the cover image which is courtesy of myself.

All statistics courtesy of Pro Football Reference unless noted.