49ers Film Room: Mid Season Run Defense

In the preseason, we previewed the potential schematic issues in the San Francisco 49ers run defense under defensive coordinator Jim O’Neil, which turned out to be prescient. Today, we’ll look at a new and improved run defense.

Throught the first eight games, the 49ers run defense surrendered 193 yards per game, allowing a 100 yard rusher in seven of those games. Over the last three games, the run defense has surrendered 115 yards per game, somewhat inflated by the Patriots game in inclement weather and a 44 yard run by Patriots running back LeGarrette Blount.

I’ve written about the run defense here and here prior to, and during, season.

Although they have still given up 100+ yards through the last three games, there is a noticeable difference both schematically and in personnel.

PERSONNEL UPGRADE

Until the bye week, nose tackle Glenn Dorsey (#90) only played in 4 games and played roughly only 20% of the defensive snaps. Since returning full-time to the lineup, he’s averaged over 50% of the snaps.

There is no doubt he is a key player on this defense and his return has allowed the 49ers to use rookie defensive end DeForest Buckner in his more traditional 5 technique end role as well using rookie defensive end Ronald Blair, whose average snap count has gone from 10 to 30 since the bye week and can anchor the 3 or 5 technique.

It’s also worth noting that Miami is ranked third in Football Outsiders rushing DVOA and Arizona at week 10 was ranked 11th in rushing offense DVOA.

How have these players impacted the performance of the run defense and what schematic changes are noticeable?

SCHEMATIC CHANGE

Through the first eight games, the 49ers struggled with schematic weaknesses and information overload. Too often, O’Neil put his defenses out of position with little adjustments made throughout the course of each game to the defense’s run fits.

A typical alignment might look something like this:

Nose tackle Mike Purcell is shaded just to the left of side of the center, and presumably responsible for the weak-side A-gap. At the snap, you can see he picks the wrong run fit, attacks the strong-side gap, and leaves the linebackers exposed to the blockers.
Purcell should have pinched that weak-side A-gap and this would’ve spilled the running back to Bowman who could’ve made the play. Instead, Christine Michael goes untouched for a 41-yard touchdown.

The 49ers have also suffered from information overload and confusion. The below example of run fits gone wrong comes from the 4th quarter. The Bills are in 21 personnel (two running backs, one tight end, two receivers) are running power to the right.

The defense breaks down immediately after Lynch sets the edge. Both Tank Carradine (#95) and Bethea attack the C gap leaving the play side B gap exposed for McCoy to run through. Bellore executes the wrong-arm technique on Bills lineman Richie Incognito spilling McCoy outside but no one is there to clean up the gap.

So what has changed?

It’s important to note that in the next series of film, the 49ers shut down these team’s primary threat by maintaining gap integrity, staying disciplined in assignments, winning one-on-one battles at the point of attack, and flowing to the football once the ball-carrier was determined.

The first noticeable thing is the defensive alignment that closely resembles a more Rex Ryan/Mike Pettine flavor. Afterall, O’Neil is part of that coaching tree. I covered the Rex Ryan influence here, but briefly, we’re seeing more hybrid 4-3/3-4 front’s being employed. By this I mean that one side of the defensive line 1-gaps their assignment (4-3) and the other 2-gaps their assignment (3-4).

Below are two still images that more closely resemble the Ryan/Pettine school of defense, one from O’Neil’s time in Cleveland and one from the Miami game.

(Cleveland 2015)

(San Francisco mid-season 2016)

The 49ers are entrusting their linemen more with certain 2-gap responsibilities and playing to their strengths, highlighted by Dorsey’s role as the 0-technique nose tackle. Buckner’s time in the 5-technique slot. Dorsey will shade just to the outside of center sometimes on certain downs but will either take on the center or pinch the A-gap.

So let’s look at the game film. Pay particular attention to the gap and leverage assignments by the front seven.

In week 10 against the Cardinals, Dorsey’s first significant time back in the lineup, the 49ers held running back David Johnson to 55 yards on 19 carries. They did this by playing disciplined defense, sticking to their assignments, and maintaining their gap integrity. While it’s obvious they game-planned to stop the run, do not discount this new found discipline.
From the above image, the Cardinals are running power to the left. Buckner is in the 5-technique and Dorsey is shaded just to the left of the center between the 0 and 1 techniques.

Buckner notices run left and takes away the gap to his right, allowing linebacker Nick Bellore to shoot the gap and blow up the lead blocker while Dorsey and linebacker Gerald Hodges (#51) make the stop.

The Cardinals are running zone to the right. Buckner chips his blocker and delays him just enough to keep Hodges (#51) free to scrape through the gap as Johnson bounces outside.

Dorsey prevents the cutback by pushing the center into to the backfield. Defensive end Quinton Dial (#92) and the rest of the defense to the right maintain great outside leverage that forces Johnson to cut back and up but not before he is swallowed by a swarming defense.

The Patriots line up in a heavy personnel tackle-over formation with two offensive tackles to their right and run power to that side. Once again, Dial eats up the double team block that keeps linebackers free. Hodges notices the play direction and pulling guard and scrapes to fill the void left by Dial’s blockers. He attacks the inside shoulder of the guard and blows up the running back in the process.

On the same side as Dial, outside linebacker Ahmad Brooks (#55) also maintains outside leverage and easily beats the second tackle to the outside with a swim move forcing the running back into the middle and makes the play with Hodges.

Ajayi bounces outside but notices Bellore, linebacker Eli Harold (#58) and Buckner all have outside leverage on their defenders, hesitates, and cuts back up the field only to be stopped by Harold.

Next: Why Chip Kelly is the best choice for head coach after 2016

It’s clear defensive coordinator Jim O’Neil has made meaningful adjustments to his scheme and can fit his players to it. This should give us pause because I do not think he is the right guy to lead the defense beyond this season. But for now, fans should be happy with the progress the young players are making should O’Neil in fact not be with the team next season.

All images courtesy of NFL.com and NFL GamePass.

All statistics, records and accolades courtesy of Pro Football Reference unless otherwise indicated.