Can Manning Crack the 49ers' 3-4?

QB Peyton Manning (Stephen Dunn/Getty)

The 49ers run a very vanilla version of the 3-4 defense, but what does that mean? Brad Keller takes a deeper look.

Historically, the 3-4 defense has been a challenge for Peyton Manning and the Colts blocking schemes.  The New England Patriots, San Diego Chargers, and Pittsburgh Steelers have all presented a stiff challenge to Manning at one point, although he has had much better luck against the hybrid 3-4/4-3 defense that the Baltimore Ravens deploy.

A key mystery for Manning and the Colts offensive line has always been divining where the fourth rusher was coming from, where any additional pass rushers might strike, and the gaps, twists, and confusion that a defense like the 3-4 can create given the personnel groupings in place.

So far this season, Manning has carved up the 3-4 defenses of the Jaguars, Dolphins, and Cardinals.  On Sunday, he faces an interesting challenge in the 3-4 defense that San Francisco uses as its base package.  The 49ers run a unique flavor of this defense in that it is almost completely vanilla.

They don't use a lot of exotic looks, they don't vary their formations by having two down linemen, re-positioning their linebackers or linemen, they don't disguise their intentions, and, for the most part, don't even put eight men in the box or run Cover 2, as San Diego, Pittsburgh, and New England have been known to do.  On Sunday, it is highly unlikely that they will change or shift coverages, use different personnel groupings, or rush more than four players on most downs.

Willis is the 49ers most dangerous defender
Getty Images

For most 3-4 defenses, stopping the run up the middle begins and ends with their nose tackle.  This is not the case in San Francisco, as nose tackle Aubrayo Franklin is not a particularly dominant player at the point of attack and does not generally seek to occupy blockers.

His game is penetration, disrupting the gaps at the line of scrimmage and allowing talented and active inside linebackers Patrick Willis and Scott McKillop — or starter Takeo Spikes, if healthy — to slip through the cracks and get to the ball carrier.  Right end Justin Smith is an exceptional two-gap defender, but he often slides inside at the snap and occupies or penetrates the gap between the guard and the tackle.

The interesting part of that strategy is that San Francisco has not been shredded on the edge, due mostly to the fact that weakside linebacker Parys Haralson is very good at taking on blockers and disengaging in enough time to make the tackle.  This is really the only aspect of the defense that is unique or exotic.  The Jacksonville defense actually showed Indianapolis more looks and combinations in Week 1 than the 49ers showed Houston in Week 7 and Week 1 was the first real game the Jaguars defense played in the 3-4.

Willis has been known to blitz during the course of the season, as evidenced by his three sacks so far in 2009, but he did not blitz Matt Schaub at all in Week 7.  Ordinarily, Haralson comes up in run support or drops back in coverage and Manny Lawson is the fourth rusher.  Willis and McKillop or Spikes are responsible for stopping the running game between the tackles and covering the short area of the field in the passing game. On very rare occasions, they run stunts or twists with the inside linebackers.

That kind of takes away the mystery in the defense.  For Manning, who is accustomed to trying to interpret complicated and constantly shifting formations when he comes to the line, the lack of movement and shifts from the 49ers may be welcome, but it could also be jarring.

In the secondary, they play mostly man coverage and very rarely deploy a zone or Cover 2 look.  They are confident that cornerbacks Nate Clements, Dre Bly, and Shawntae Spencer can handle their respective assignments and that safeties Deshon Goldson and Mark Roman will help out over the top.  The biggest weak spot in the 49ers defense is their safeties, as starters Michael Lewis and Reggie Smith have missed a great deal of time due to injury — and they may be out of the lineup again on Sunday. Manning needs to exploit this weakness in order to be successful.  Otherwise, the efficient San Francisco defense will try to wear him down and make him flinch.

The devil for the 49ers defense is most certainly in the details.  They stick to their assignments and trust in the simplicity of their scheme.  Manning and the Colts will need to be just as detail oriented, stay focused, and not allow themselves to slip, because the San Francisco defenders will pounce on any mistake.

Manning has shown time and time again that he has tremendous mental fortitude and that his level of concentration does not show any kind of fatigue. 

The issue is that every other 3-4 defense he's faced this season has, on numerous critical occasions, been the first to flinch, the first to slip up.  That will not happen to this 49ers defense on Sunday.  They're too vanilla to give Manning anything to exploit.

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