Cary Edmondson-USA TODAY Sports

Cary Edmondson-USA TODAY Sports


Film From the Field House: How Kyle Shanahan and the 49ers Use the 20 Series

Bret Rumbeck
May 18, 2020 at 5:00 PM


The evolution of professional football from decade to decade is a conversation that never ceases to leave me in awe. Equipment gets stronger and lighter, while athletes eat and train better. The result is a faster game, though football's rudimentary foundations remain unchanged.

San Francisco 49ers head coach Kyle Shanahan's mastery of professional football has given him many labels, including soothsayer and genius.

Predicting the outcome of a play is impressive, but for me, Shanahan's modifications to the original West Coast Offense is his most remarkable accomplishment.

In the 1982 49ers playbook, the late Bill Walsh noted four different drop back passing series: 20s, 50s, 70s, and 80s. The first number indicated the series, and the second was related to which side the Y receiver aligned. For example, '27' would put the tight end on the left or odd side of the formation, while '24' would place the tight end on the right or even side.

The second number also meant different actions for the backs. '24' would be a different flair action for the running backs than '26.'

But the one constant in the 20 series was what both backs did - they split in opposite directions to pick up a linebacker or enter the play on a short route.

Some coaches call the 20 series 'split-flow' protection; Walsh described it as 'divide' or 'split' protection. Don't worry about the terminology; keep your eyes on the running backs and tight end.

Shanahan still uses the 20 series today, although he does not call it often. As previously noted, 'Jet' and 'Scat' protections dominate the 49ers' drop back offense, with scattered use H2/H3 and 64/65 protections.

When the 49ers use 20/21, you'll see six men protecting the quarterback - five offensive linemen and the Y receiver. Typically, 20/21 is used with a single back, and he has a free release.

The center declares the Mike linebacker, setting the protection for the line, which is responsible for the four defensive linemen and the Mike. The Y receiver has responsibility for the Sam, but he can release into the play if the Sam does not blitz, or the offensive tackle takes over the defensive end.

You've probably watched enough football to notice the center declare a Mike backer, and then the quarterback changes the Mike midway through the cadence. The quarterback's ability to 'Re-Mike,' designating a Sam or Will as the Mike linebacker, changes the line's responsibility.

24-25 Chip is all that's left of Walsh's original 20 series. It is seven-man protection, with the offensive line responsible for the four defensive linemen and the Mike. In this series, the Y has a free release, and the backs divide to check outside linebackers.

The strong back reads Sam to the strong safety or corner, while the weak back reads the Will to the free safety or corner.

Week 5: 3rd Quarter - 3rd and 6 at the SF 14 (13:57)



Shanahan called a (3)24/25 protection early in the 3rd quarter against the Cleveland Browns. Running back Raheem Mostert and fullback Kyle Juszczyk made similar reads starting at the outside linebacker and ending with the safety or cornerback.


Both gave an assist, or chip, with their respective tackles. Mostert ended up running into the flat, while Juszczyk stayed in to help pick up the linebacker.

Week 9: 4th Quarter - 3rd and 11 at the SF 16 (8:34)



Shanahan used 25 protection when the 49ers needed a big play on third down against Arizona. As usual, Shanahan put a twist on the call, instructing tight end George Kittle to 'fly' into a gold formation.


Once left tackle Justin Skule had control of the defensive end, Kittle was able to release into the play, while running back Tevin Coleman worked with right tackle Daniel Brunskill to halt defensive end Terrell Suggs.

Later in the game, Shanahan called the same play but flipped it to Gold Right Ace and gave both backs a free release. Quarterback Jimmy Garopplo found wide receiver Emmanuel Sanders on the play for 16 yards.

The 20 series is a dying protection in the modern NFL. There's no point in using two backs to protect a quarterback when a run-pass-option play can freeze a linebacker in his tracks.

However, with the 49ers using two-back sets on nearly 40% of its offensive plays, it makes sense for Shanahan to keep the protection in his playbook.

All images courtesy of NFL.com.
All statistics courtesy of Pro Football Reference unless noted.
  • Bret Rumbeck
  • Written by:
    Bret Rumbeck has been writing about the 49ers since 2017 for 49ers Webzone and 49ers Hub. He is a Turlock, CA native, and has worked for two members of the US House of Representatives and one US Senator. When not breaking down game film, Bret spends his time seeking out various forms of heavy metal. Feel free to follow him or direct inquiries to @brumbeck.
The opinions within this article are those of the writer and, while just as important, are not necessarily those of the site as a whole.


1 Comment

  • T
    Nice writeup. SF loves 21 personnel so it makes a lot of sense to retain lots of the 20s stuff. With both Staley and McG missing time in 2019, split back protection made a lot of sense to help out Brunskill and Skule on key downs.
    May 19, 2020 at 9:08 AM
    0

Facebook Comments



More San Francisco 49ers News



49ers Notebook: OL Spencer Burford looks ahead to starting; WR Ray-Ray McCloud's reflections on Kyle Shanahan; Shanahan pleased with Javon Kinlaw

By Kirk Larrabee
Aug 9

The 49ers are just three days away from their preseason opener against the Green Bay Packers (8:30 p.m. ET/5:30 p.m. PT, Friday), a game that will give 49ers fans the chance to see a number of their team's players in on-field action for the first time. Two particular newcomers of interest to keep an eye on Friday night will be offensive lineman Spencer Burford and wide receiver/return specialist Ray-Ray McCloud. Burford is progressing towards starting as a rookie at right guard after being selected by the 49ers in Round 4 of the 2022 NFL Draft, while McCloud will be making his 49ers preseason debut after signing with the team as a free agent in the offseason. McCloud is expected to be the primary return specialist for the 49ers this season, but there's a chance he could also



Kyle Shanahan: 49ers were 'locked in' on Trey Lance and Mac Jones leading to 2021 draft

By David Bonilla
Aug 9

San Francisco 49ers head coach Kyle Shanahan joined the I Am Athlete podcast and was asked about the process leading to the team selecting quarterback Trey Lance with the No. 3 overall draft pick last year. There was a lot of speculation surrounding who the 49ers were looking to draft after trading up from the No. 12 spot. Many felt Shanahan had targeted quarterback Mac Jones, while many fans scoffed at the idea. Jones was a target—along with Lance. "We did the trade so early that it made me feel good about it because I knew before we did it how I felt about the quarterbacks," Shanahan said,



Could Kyle Shanahan keep Jimmy Garoppolo? Who plays Friday night? And more 49ers mailbag questions answered

By Marc Adams
Aug 10

The San Francisco 49ers have a game this week. Not one that counts, or one that even has much meaning. Although it is meaningful to some young players trying to make the team. Friday night we get our first look at some of the new 49ers we've yet to see, as San Francisco squares off with the Green Bay Packers. Who will play? Who won't play? What if Trey Lance looks bad? We have answers to all your team questions and more. Let's open the mailbag. What will Shanahan do if Lance stays around a 50 percent comp % in camp and preseason? Will he still get rid of Jimmy and still start Lance? - Daniel K. Jimmy Garoppolo is still with the team, but only because a decision on what to do with him has yet to be made. He isn't practicing with the team, he isn't



Kyle Shanahan reveals two new 49ers injuries, one which sparked Tuesday's brawl

By David Bonilla
Aug 5

San Francisco 49ers head coach Kyle Shanahan spoke with reporters ahead of Friday's practice, providing some injury updates during the conversation. First, he revealed that offensive lineman Jaylon Moore would miss some time with a lower leg strain. The other injury was to wide receiver Marcus Johnson, who is in the concussion protocol. The injury occurred on Tuesday, the same day as the brawls between linebacker Fred Warner and wide receiver Brandon Aiyuk. According Shanahan, Johnson was the recipient of a big hit from the star linebacker, causing the injury and sparking the scuffle. "I love the intensity of it, but I don't think you have to fight to be intense, though," Shanahan said of the brawls. "Scuffles are scuffles. Then


Featured

More by Bret Rumbeck

More Articles

Share 49ersWebzone