How the 49ers 21 personnel became potent enough to be dubbed the ‘Death Lineup’

ESPN’s Mina Kimes and The Athletic’s Nate Tice have recently referred to the 49ers' 21 personnel unit (2 backs, 2 wide receivers, and 1 tight end) as the "death lineup."

As Tice pointed out on Twitter, this moniker is a reference to the most potent lineup in the NBA from 2014 to 2019, on a Golden State Warriors roster featuring Steph Curry, Klay Thompson, Andre Iguodala, Kevin Durant, and Draymond Green.

San Francisco runs more 21 personnel than any team in the league, and that’s been consistent under Kyle Shanahan. But the change in playing style from new players, such as Christian McCaffrey, has helped take the 49ers' offense to levels Shanahan has likely only dreamt about since taking over as the team’s head coach.

Shanahan has evolved with the NFL without comprising the primary principles of his offense. Before acquiring Christian McCaffrey via trade, the 49ers dropped back to throw the ball 34 times in 21 personnel for the first seven weeks of the season while running the ball 62 times.

Since McCaffrey’s been in San Francisco, the 49ers upped that drop-back number to 110 out of 21 personnel while still leaning on the ground game with 132 rushing attempts.

San Francisco’s peak 21 personnel — the so-called ‘death lineup’ — unit is McCaffrey, Kyle Juszczyk, George Kittle, Brandon Aiyuk, and Deebo Samuel. Against the Seahawks, that lineup was on the field for 17 snaps. They amassed 261 yards averaging over 15 yards per play. While seemingly unsustainable, this team has been averaging nearly five touchdowns a game since Week 13 ever since Brock Purdy took over.

Formation free-for-all

The most significant advantage the 49ers have offensively is their speed. Four of their eligible receivers run a 4.4 40-yard dash or better — Kittle confirmed last summer he ran in the 4.4s.

When Juszczyk and Kittle are on the field, defenses are forced to leave their third linebacker to stop the run. But while common sense would tell you the Niners will run a standard I-Formation with two backs in the backfield, Shanahan has done anything but since the acquisition of McCaffrey.

Shanahan’s gone from an edgy play-caller with a new wrinkle here or there to a mad scientist, finding out on the fly whether his new concoctions are working. Here are the different formations the Seahawks dealt with when the Niners' 21 personnel was on the field:

This look doesn’t tip the offense's hand about which way they are running.

On this play, you have three eligible receivers to one side, with two in condensed splits about three yards away from the line of scrimmage. Oh, and Deebo is in the backfield.

The above look gives the illusion that the 49ers are running a play to the top of the screen, where three eligible receivers (Juszczyk, Kittle, Aiyuk) are positioned, but the play they actually ran was a shot play to Jauan Jennings toward the bottom of the screen.

These are the first four offensive plays from scrimmage, mind you.

Blocking is the new one-handed catch for receivers

During the past month, the 49ers' off-speed pitch has been using Jennings as a deep threat. I asked Shanahan earlier in the week why they use Jennings in that role. Unsurprisingly, it’s thanks to his aggressiveness as a blocker:

“He got those deep opportunities because of what he does in the run game. The way Jauan goes after people, blocking, is the reason people react to try to not get hit by him and go up and stop runs. You saw what he did to them in the last game on those looks, that’s why he got the pass plays off of it.

He was really open because he blocked so well and that’s what he did a good a job of. I thought that ball wouldn’t be quite as far down the field, where it got close to [Seattle Seahawks S Quandre] Diggs, but that’s where Brock put it and it ended up being a perfect spot because Jauan went and got it and Jauan will do anything you ask him to do, and he’s a really good player.”

During the game's second drive, McCaffrey’s 68-yard rush, the fourth-fastest carry of the Wild Card weekend, was courtesy of a creative Shanahan design out of 21 personnel.

On the surface, it looks like your typical 2x2 formation. Then, the pre-snap motion gives San Francisco the numbers advantage to one side. Juszczyk has an easier angle to block an oncoming linebacker, while another linebacker has the luxury of Trent Williams running at him full speed.

The result of the play:

The linebacker, cornerback, and safety to the bottom of the screen had little to no interest in competing on the play, and the 49ers took full advantage.

Williams and Kittle have earned reputations as the best blockers at their positions. The same wasn’t true a year ago for Aiyuk, as he found himself in the doghouse. That’s changed this season.

On Wednesday, Shanahan was asked about Aiyuk’s blocking prowess and spoke about how the mindset of the 49ers' best players is what separates them from the rest of the league:

“I think it always helps when you have length and size and I think he does have that. I think it’s the mindset of all our guys though. I think we do have a lot of good players. What I like to say separates us from other teams with good players is our good players really block too, whichever one of our five guys has the ball, the other four are blocking as good as anyone. And Brandon does that as good as anyone, but I think all our guys do also.”

While perimeter players blocking through the whistle doesn’t absolutely add-up to the value equal of the Splash Brothers' 3-point shot, it has been the “Odell Beckham Jr. catch” for San Francisco this season — whether or not we have seen it in the highlight reels.

You won’t find a 49er play that’s gone for 40+ yards this year where a player wasn’t blocking somebody down the field. Shanahan has gotten his skill players to buy in, and the reward has been more than fruitful for an already efficient offense.

Fail-safe is the future

Shanahan has modeled the 49ers into the ideal fail-safe offense. In seasons past, there was always too much on one individual’s plate, forcing a secondary player that wasn’t equipped to win the necessary matchup.

Fielding a roster with only good players doesn’t hurt, but we’re seeing the dividends of what happens when each player has the same probability of failure. The outcome is an offense that’s maximized, which is why we see the scoreboard starting with a 3 or a 4 after each game.

Traditional thinking will lead you to believe a position has do to A-B-C, while another position is responsible for X-Y-Z. Tying the Warriors back into the discussion, you don’t need your center to be the rim protector. If your small forward can block shots and shoot 3s while your power forward can keep bigs out of the paint and rebound, you’ve solved the problem.

With Shanahan, we’re seeing an essential change to the game of football before our eyes. He’s far from the first coach to use a running back as a pass catcher — hello, Roger Craig — but we’re seeing the extremes of positionless football.

McCaffrey lines up as a running back, but he also plays out-wide at receiver or in the slot. Juszczyk has played every position besides quarterback this season. Deebo looks like the best running back in the league when the ball is in his hands.

As was the case for the Warriors, it helps to have transcendent talent. NBA teams don’t often have the luxury of signing a 7’ wing defender that shoots 50/40/90 that can protect the rim.

What San Francisco is pulling off should be filed under “don’t try this at home.” We’re still waiting for “the next Deebo” to show their face. McCaffrey isn’t limited to catching screen passes. What other running backs are asked to run these types of routes?

We’re not far away from your running back being the ultimate utility position on offense. McCaffrey, the team’s go-to player, has the label of a running back but catches slants on first downs.

The 49ers' best running back might be their receiver, that excels after the catch with acceleration in a way that would make a cheetah blush. Their top red zone target isn’t your typical stud wide receiver that the Bills or Bengals have, but an uber-athletic blocking tight end that’s a mismatch inside the 10-yard line.

The primary discussion around the 49ers this season, a topic that’ll continue in the offseason, will surround the quarterback. Despite three different players under center, the continuity has remained stable with the head coach and stars at the skill player position.

Shanahan’s constant usage of pre-snap motion only causes more havoc as opposing defenses play catch up — literally and figuratively — to the 49ers' 21 personnel.

During last year’s Wild Card game against the Cowboys, San Francisco threw the ball seven times in 21 personnel. They might top that number in the first quarter with this year’s “death lineup.”