49ers Betting on the D-Line by Cutting Marcus Rush

In cutting Marcus Rush from the 53-man roster, the San Francisco 49ers are betting on the strength of the D-Line. Here we examine why they made that gamble.

Six tackles, two forced fumbles and an interception in preseason were not enough to convince the San Francisco 49ers to give linebacker Marcus Rush a spot on the active roster in a decision that left many bewildered.

The rest of the NFL appears to agree with the 49ers though, with San Francisco able to stash Rush on the practice squad after he went unclaimed on waivers.

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Yet, with Aaron Lynch suspended for the first four games of the season, cutting Rush and leaving just three outside linebackers on the roster represents a gamble for a San Francisco team that had just 28 sacks in 2015.

So what motivated the Niners to not even give Rush a four-game tryout until Lynch’s return? Here we examine why San Francisco cut bait with its preseason star.

Run Defense

Prior to Rush getting cut, Pro Football Focus’ Jeff Deeney highlighted his poor play against the run, which could have been a significant factor in the 49ers’ decision:

After struggling significantly in defending the run in 2015, San Francisco cannot afford to carry a surplus of players who perform poorly against the ground game this season.

San Francisco ranked No. 23 in run defense last term, per Football Outsiders, and faces the likes of Todd Gurley, Ezekiel Elliot and David Johnson in the opening five weeks of the season.

Some may argue Rush’s difficulties against the run are immaterial because he would only likely be used as a specialist pass-rusher in sub packages.

The problem with deploying Rush in sub packages is the Niners have been particularly susceptible to ground game in nickel and dime defenses.

According to PFF, the 49ers surrendered 5.13 yards per carry in sub packages in 2015, the fourth-worst mark in the NFL.

If the 49ers are to have an improved defense in 2016, they must bring that number down. And the statistics suggest Rush would not have helped them do that.

Versatile Secondary Players

It is accepted convention in the NFL you can never have enough pass-rushers. But simply having a plethora of edge rushers is far from the only way to engineer pressure.

The age of the hybrid linebacker/safety has given defenses blessed with such players extra versatility. And the Niners happen to possess one such talent in Jaquiski Tartt.

Tartt still has a long way to go in coverage. But the former Samford safety is proficient against the run and gets downhill in a hurry. And it was no surprise to see him drop down in the box during his rookie year.

The presence of Tartt allowed the 49ers to load up in the box and disguise their pass-rushers — a tactic they should be looking to utilize again in 2016. Though they will not be able to do so with cornerback Will Redmond, who was placed on injured reserve on Monday.

Remond had looked like he could make an impact as a blitzer, showcasing his speed register a sack in his preseason debut against the Packers.

With Redmond out of the picture, the similarly fast Keith Reaser — who has 4.3 speed — and nickel corner Chris Davis are candidates to rush the passer off the edge and down in the box.

Having secondary players who can close quickly and one of the better pass-rushing inside linebackers in the NFL in NaVorro Bowman should again allow the Niners to generate pressure by stacking the box and disguising blitzes, something that may have come into consideration when San Francisco decided to roll with just three outside backers.

The D-Line

The simplest explanation is usually the correct one. And, in analyzing why the 49ers cut bait with Rush, the most obvious reasoning is that San Francisco has tremendous faith in its defensive line.

San Francisco has of course invested very heavily in the D-Line, with consecutive first-round picks spent on Arik Armstead and DeForest Buckner in the last two years.

Injury prevented Armstead from showcasing his development in the preseason while Buckner’s impact was minimal.

But Armstead, coming off a promising rookie year, was seen as the big winner of training camp, with Joe Staley labelling him “10 times different” than in 2015 — per Chris Biderman of The Niners Wire — and Buckner comes into the NFL having racked up 10.5 sacks in his final college season.

San Francisco’s faith in that former Oregon duo is certainly understandable. And the Niners can afford to have similar belief in fifth-round pick Ronald Blair.

Blair has shone throughout the preseason despite being undersized at 6-foot-4 and 270 pounds, generating push up front from the interior of the D-Line and the edge.

He is not a nuanced pass-rusher and Blair often has no answer when his initial rush stalls. But he uses his hands very well to shed blockers and is quick to find the football.

With an impressive swim move at his disposal and the ability to play off the edge, it may well have been Blair who forced Rush off the roster.

The 49ers can use Blair as a stand-up rusher across from Tank Carradine, who has himself impressed in preseason with two sacks, and also have him push the pocket from the interior.

For all Rush’s extremely strong play, he does not possess the versatility of a defender like Blair. And Rush also has the disadvantage of being undersized and playing the run poorly.

Rush’s production indicated he could have been a contributor this season. However, the 49ers are gambling on the promise of a very talented young D-Line to push the pocket from the interior while hoping Carradine’s transition to outside linebacker can continue to be a successful one and that pressure can be manufactured from the secondary.

Should they look losing that bet, then don’t rule out Rush earning the promotion many believe he already deserves.

Next: Bruce Miller Arrest: The 49ers Are Justified in Releasing Their Former Tight End

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