Why the Miami Dolphins Defense Is the Key to an Upset of the San Francisco 49ers

Erik Frenz@ErikFrenzSenior Writer IDecember 7, 2012

ORCHARD PARK, NY - NOVEMBER 15: C.J. Spiller #28 of the Buffalo Bills runs against  Cameron Wake #91 and  Karlos Dansby #58 of the Miami Dolphins  at Ralph Wilson Stadium on November 15, 2012 in Orchard Park, New York.  (Photo by Rick Stewart/Getty Images)
Rick Stewart/Getty Images

The San Francisco 49ers looked downright unstoppable for weeks under new starting quarterback Collin Kaepernick.

It won't be easy, but if the Miami Dolphins want to slow down the 49ers' high-efficiency offense, it has to start with a top-notch performance from their front seven against the run.

The goal is to make the 49ers play outside of their strengths, which are not just in running the ball, but how they use the run to set up the passing game.


The 49ers love to bring out their heavy personnel groupings, whether they're running or throwing the ball. Their effectiveness in the power running game allows them to throw the ball well out of those formations because defenses stack the box (as shown above).

The problem with stacking the box is that it's not always effective, and when it's not, the defense is opened up to a big gain.


Frank Gore followed the lead block of his fullback and got to the second level for a 23-yard pickup. 

The 49ers rank third in FootballOutsiders.com's adjusted line yards when running up the middle or off a guard on the inside. They also only get stuffed on 16 percent of their runs, the fourth-best average in the NFL.

Notice on the run above, guard Mike Iupati won his matchup outright against defensive tackle Michael Brockers (circled in blue) while fullback Bruce Miller (yellow line) and tackle Joe Staley (circled in red) sealed the edge. With no linebackers left to make the stop, Gore picked up a head of steam and thus the long gain.

It also bears mentioning that the 49ers rank first in second-level rushing yards (via FootballOutsiders.com).

Slowing them down on the ground is easier said than done to be sure and the Dolphins have already struggled this year with top rushing attacks.

They've given up over 100 yards rushing in five of their 12 games this year, and almost always to good running teams—of the five teams, only the New York Jets rank outside the top half of the league in rushing YPA. That being said, of the seven teams they've held to under 100 yards rushing, only two rank in the top half of the league in rushing YPA.

If they're able to ground the 49ers' ground-and-pound attack, it will in turn ground the 49ers' aerial assault as well.

The sample size is very small (131 total dropbacks), but thus far, the 49ers have used play action on over one-third of Kaepernick's dropbacks (44 play-action dropbacks, 33.6 percent, via ProFootballFocus.com).


This is a play designed to take advantage of aggressive safety play against play action. The 49ers only had one receiver out wide on this play and the Rams stacked eight men in the box. 


They put two defenders on Randy Moss deep as he runs a go route up the left side, opening the short area of the field for an easy completion to the fullback Miller out of the backfield. 

Even when a defense does everything right, the 49ers can still get their licks in.

It's easy to see why an effective run defense is the key in shutting down the 49ers offense. What's not so easy to see, though, is whether the Dolphins can be successful enough against the 49ers to make their trip out west worth their while.


Erik Frenz is the AFC East lead blogger for Bleacher Report. Be sure to follow Erik on Twitter and "like" the AFC East blog on Facebook to keep up with all the updates. Unless specified otherwise, all quotes are obtained firsthand or via team press releases.