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49ers-Rams preview: Beating the blitz, St. Louis's boom or bust run D, shutting down Austin Davis

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The San Francisco 49ers travel to St. Louis to take on the Rams on Monday Night Football. We take a look at why the Rams might be better than their record would indicate and what the 49ers will need to do to come away with the victory.

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Coming into the season, if there was one thing you would have expected the St. Louis Rams to excel at, it would have been rushing the passer.

On the coattails of a deep and talented defensive line rotation led by All-Pro Robert Quinn, the Rams put opposing passers on their backs 53 times in 2013, leading the league in Adjusted Sack Rate. After general manager Les Snead added defensive tackle Aaron Donald — the best interior pass rusher available — to the mix in the first round of May’s NFL Draft, the punishment they would inflict on quarterbacks became terrifying to think about.

Yet, as the 1–3 Rams look up at the rest of the NFC West in the standings, they’ve sacked the quarterback exactly… once. You know, because, football.

The pass rush wasn’t helped when St. Louis lost defensive end Chris Long to short-term IR after suffering an ankle injury against Minnesota in Week 1. Long is obviously a very good player, but his absence is not nearly enough to explain the pass rush’s dramatic drop from first to worst. Quinn, Donald, and Michael Brockers give the Rams three additional first round picks along the defensive line, not to mention quality rotational players such as Kendall Langford, William Hayes, and Eugene Sims. There’s more than enough talent here to make life difficult for opposing quarterbacks.

At this point, it’s reasonable to wonder whether the change in defensive scheme has had a negative impact on the Rams’ talent up front. Gregg Williams, who took over for Tim Walton as defensive coordinator this year, has a reputation for blitzing heavily. One of the biggest questions facing the Rams defense before the season was whether Williams would stubbornly stick with his aggressive, blitzing style or tone things down a bit considering the talent he was working with along the defensive line. Through the first quarter of the season, the answer has been clear.

Under Williams, the Rams are blitzing on nearly half of pass plays, up significantly from last season. As that lone sack indicates, all of those extra pass rushers haven’t been able to find their way to the quarterback and it’s leaving St. Louis’s young secondary exposed on the back end; entering Week 6, the Rams have had the second-worst pass defense in football.

To the credit of the secondary — and despite one of the worst blown coverages you’ll see on this Dez Bryant touchdown — the Rams have done a great job preventing big plays in the passing game. You would often expect a team that blitzes unsuccessfully as often as the Rams do to give up a lot of long passes. Yet, the eight pass plays of 20 yards or more allowed by the Rams defense coming into the week was the lowest total in the league. Rather than picking up huge chunks of yardage at once, offenses have been able to take advantage of the man coverage behind St. Louis’s blitzes for consistent yardage in the short and intermediate areas.

Colin Kaepernick has been very good against the blitz over the course of his career and should have opportunities to exploit St. Louis’s secondary as long as the protection doesn’t break down immediately. Outside of a stretch in the middle of the third quarter that saw Kaepernick sacked on three consecutive dropbacks, San Francisco’s offensive line performed much better in pass protection last week against Kansas City’s stellar pass rush. It will be important that they improve on that encouraging performance and not be the reason Robert Quinn and co. get back on track.

Boom or Bust Run Defense

On the surface, St. Louis’s 18th-ranked run defense is nothing to be concerned about for a San Francisco team that’s rushed for nearly 400 yards over the last two weeks. Dig a bit deeper and you’ll find a defensive line playing incredibly well but all to often being let down by their teammates on the second and third level of the defense.

As alluded to, the struggles of the Rams defensive line rushing the passer have not carried over to the run defense, where they’ve been fantastic so far this season. St. Louis ranks fourth in Football Outsiders’ Adjusted Line Yards — which attempts to isolate the defensive line’s impact in the run game from the rest of the defense. With Donald (5 TFL), Quinn (4), and the rest of the defensive line frequently blowing runs up in the backfield, the Rams have recorded 40 tackles for no gain or a loss, giving them the highest stuffed percentage in football.

It’s in the instances in which the Rams defensive line isn’t able to cause havoc in the backfield that teams are able to make them pay in the run game. St. Louis’s linebackers tend to play up closer to the line of scrimmage than typical linebacker depth and are quick to fly downhill once they read run. That has undoubtedly contributed to a number of those tackles for loss. But when those linebackers read the play incorrectly, overpursue, or generally find themselves out of position — something that happens too often — running backs that manage to break through the Rams’ first line of defense are finding lots of green grass in front of them.

Combine that with sloppy tackling and you get a defense that is giving up a lot of big plays in the run game. Despite playing one fewer game than most teams as a result of their Week 4 bye, no team has given up more runs of 15 or more yards than the Rams. It’s one thing to have DeMarco Murray ripping off those types of runs behind one of the best offensive lines in football, but giving them up to Bobby Rainey and the Bucs is another story.

Last week against the Chiefs, the 49ers were able to pickup consistent yardage on the ground throughout the game. San Francisco’s success rate (based on Football Outsiders’ thresholds for a successful run) on carries from Frank Gore and Carlos Hyde was 60.7 percent, which is just shy of DeMarco Murray’s success rate through five games. Gore alone was able to pick up sufficient yardage towards a new set of downs on an absurd 72.2 percent of his carries.

Given St. Louis’s propensity for blowing up ball carriers in the backfield, it’s unlikely that San Francisco will be as consistent this week. The Rams use a heavy rotation along their front four, allowing them to have fresh bodies on the field throughout the game. Blocking a group that talented for four quarters is no easy task, especially when they don’t seem to get tired. There’s a solid chance we see a good number of short gains mixed with the occasional 20-yard romp through the Rams’ secondary, which can make it more difficult to sustain drives by leaning heavily on the run. But if Joe Staley and co. can find a way to limit the busts, we could see a lot of boom from the Niners running game for a third straight week.

Ascending Rams Offense

On the opposite side of the ball, the story has been the play of Austin Davis and the steadily improving St. Louis passing offense. After an absolute bomb against Minnesota in their season opener — which was so bad it continues to drag down their overall offensive ranking — St. Louis’s pass offense DVOA has increased with each passing week.

Prior to taking over for an injured Shaun Hill in the second half of that Week 1 blowout, Austin Davis had never thrown a regular season NFL pass. In three starts since then, Davis has played at roughly a league average level, which is kind of remarkable for the former undrafted free agent out of Southern Miss. Headed into the week, Davis ranked 12th in ANY/A, 13th in DVOA, and 16th in QBR.

As you would expect for such an inexperienced player, Davis will occasionally make some poor decisions and force a throw into coverage that he shouldn’t. Despite a very solid 67.8 completion percentage, Davis can also struggle with accuracy at times. But with Davis under center, the Rams’ passing offense has shown more signs of life than we ever really saw with Sam Bradford at the helm.

Unlike with Bradford — when it seemed as if receivers disappeared from his vision once they went beyond 10 yards from the line of scrimmage — Davis is far more willing to push the ball down the field. According to Pro Football Focus, just over 15 percent of Davis’s passes have traveled 20 or more yards in the air, the seventh-highest rate among qualifying quarterbacks. Finding big play threats such as Kenny Britt and Jared Cook, Davis has been able to add a much needed vertical element to the St. Louis passing attack.

Every quarterback in the league in worse with pressure, but you typically expect young quarterbacks to struggle more than most. With Davis, that hasn’t been the case through the first quarter of the season. He’s moved well within the pocket to avoid pressure and has been able to get throws off with bodies around him, which happens quite a bit.

By PFF’s numbers, only Chad Henne and Matt Cassel have been pressured more frequently than Davis, who’s faced pressure on just over 40 percent of dropbacks. Despite those less than ideal throwing conditions, Davis has completed 54.9 percent of his passes under pressure, putting him sixth among qualifiers between the likes of Drew Brees (55.6%), Andrew Luck (55.6%), and Aaron Rodgers (54.8%).

San Francisco’s pass defense also enters this game on the rise. After getting picked apart in the second halves against the Bears and Cardinals, the 49ers have worked their way back to the seventh-best pass defense by DVOA and they’ve managed to do so with a pass rush that’s MIA. A lot of that has to do with the play of Perrish Cox on the outside. Cox has been great since taking over for the injured Tramaine Brock and the 28.6 QB rating throwing into his coverage is the lowest among cornerbacks, per PFF.

There’s no reason to expect the 49ers run defense to struggle keeping Zac Stacy under wraps. Since that Week 1 matchup with Murray and the Cowboys, San Francisco’s run defense has been lights out, holding Andre Ellington, LeSean McCoy, and Jamaal Charles to a combined 3.87 yards per carry. Instead, it will be up to the secondary to continue their strong play, limit big plays down the field, and keep Austin Davis from making things interesting.

Prediction: 49ers (–3.5) over RAMS