Can Miami Dolphins' Defense Toughen Up Against the Run in 2015?

Statistically, the Miami Dolphins had one of the 10 worst run defenses in the NFL last season. They yielded 1,937 rushing yards, or 121 yards per game. They also allowed 4.3 yards per rush attempt.

Defense has long been the Dolphins' calling card, but it slipped in a big way in 2014. That's why, despite dramatic improvements on the offensive side of the ball, the Dolphins still managed to finish with the exact same 8-8 record that they had the year before.

That defense will need to return to form in 2015 if the Dolphins are going to deliver on their hopes of finally ending their playoff drought after six years out of the postseason.

On one hand, there is one very big reason they can make the necessary improvements. On the other hand, there are several other reasons they might see some trouble. That one big reason is the acquisition of free-agent defensive tackle Ndamukong Suh. The several other reasons are the question marks at linebacker.

The questions then become: How much of an impact can one man have on the run defense, and will that positive impact be enough to negate any negative impact made by the lack of answers at the second level?

Suh often gets his recognition as a pass-rusher, but it's his ability against the run that is particularly noteworthy. He notched 20 tackles for loss in 2014, the most of any defensive tackle in the NFL, according to Advanced Football Analytics. He also earned Pro Football Focus' second-highest run-defense grade of any defensive tackle in the NFL last year.

So, the easy answer to the first question would be "a major impact."

The second question is a bit harder to answer.

We've seen the impact of a dominant run-stuffing defensive tackle on the Dolphins defense in the past. Look no further than Paul Soliai for an example of how one gap-eating big man can change the complexion of the entire defense.

Who knows what the Dolphins defense would have looked like in 2014 had Soliai still been around, but one can assume it would have looked a lot like what their defense will be in 2015.

Koa Misi has shown the potential be a good middle linebacker. He has played nearly every linebacker position imaginable since entering the NFL: 3-4 outside linebacker, 4-3 outside linebacker and 4-3 middle linebacker.

Give him another year to develop—and let him develop behind a dominant defensive tackle like Suh—and he could make strides.

Jelani Jenkins showed a high ceiling of his own last year when filling in at weak-side linebacker after Dannell Ellerbe's season-ending injury. Most of Jenkins' best work, however, was in pass coverage and as a blitzing linebacker. He earned his lowest grade as a run defender.

With that said, Suh doesn't need to dominate on every play with a tackle for loss. If he can just command a double-team and keep the linebackers clean, he'll be doing more than last year's defensive tackles did.

Credit: NFL Game Rewind

Take this 1st-and-10 running play by the Baltimore Ravens, for example. The Ravens had enough men up front to account for everyone in the Dolphins' front, and none of the Dolphins defenders were able to command a double-team.

With one-on-one blocking assignments across the board, the Ravens' pulling linemen were in perfect position to get blocks on the linebackers at the second level:

Credit: NFL Game Rewind

That made for some easy cutback work for Ravens running back Lorenzo Taliaferro, who picked up nine yards thanks to solid blocking—and shaky defense. 

As a team, the Dolphins ranked 12th in missed tackles per snap. It's fair to wonder how many more missed tackles the Dolphins would have racked up if bad angles and gap discipline had been included in that analysis.

But that's exactly the kind of play that Suh would be able to help prevent. If an offensive line has to account for Suh with two blockers, that means there will be a linebacker at the second level who is unblocked and able to make a play.

And it's also not just about Suh and the defensive front. Suh will probably command a lot of double-teams, so whoever is playing next to him will have to take advantage of any one-on-one blocking assignments they see.

Suh's running mate in the starting lineup will most likely be Earl Mitchell, according to Armando Salguero of the Miami Herald. Rookie Jordan Phillips could also get some opportunities in running situations, using his 6'5", 329-pound frame and 34 ¾" arms (per NFL.com) to bull-rush blockers into the backfield.

Suh could also be in familiar company with C.J. Mosley, whom the Dolphins also signed away from the Detroit Lions this offseason.

With the arrival of Suh, it would be tough to argue that the Dolphins defense won't take a step forward.

However, it's not all about one man. It takes an entire team to play good run defense, and if a lack of discipline seeps into the front seven the way it did in 2014, the Dolphins could be in for a lot of ground-and-pound offensive strategies in 2015.

Unless otherwise noted, advanced statistics courtesy of Pro Football Focus.