This was expected to be a very good unit in 2013, with a chance of being excellent. Yet after five games and six weeks of NFL action, it just hasn't played out that way.
The rankings confirm that:
Yards per game: 25th
Yards per play: 19th
Rushing yards per game: 15th
Rushing yards per play: 17th
Passing yards per game: 27th
Passing yards per play: 21st
Interception rate: 15th
Sacks per pass attempt: 24th
First downs per game: Tied for 26th
Third-down percentage: Tied for 9th
Fourth-down percentage: Tied for 11th
Red zone percentage: Tied for 15th
Goal to go percentage: 32nd
Points per game: 20th
This group was actually to be closer to the top 10 than the bottom half of the league.
So what has happened and why is there reason to believe things are going to get better?
The answer is quite simple: injuries.
Just look at some of the injuries that have hurt the defense so far this season.
Cornerback Dimitri Patterson missed the last four games because of a groin injury sustained in the opener against Cleveland.
Defensive end Cameron Wake sustained a knee injury early in the home opener against Atlanta on Sept. 22 and has played a total of 16 snaps over the last three games.
Defensive tackle Paul Soliai sustained a knee injury in the second half of the game against Indianapolis, missed the Atlanta game, then was limited to 22 snaps in the Monday night game at New Orleans (although the Saints' offensive system might have played a part in Soliai's limited action).
Mind you, there are three key components of that Dolphins defense.
Patterson is a solid veteran who's clearly the team's second-best cornerback behind Brent Grimes.
Wake merely is the team's best pass rusher and biggest difference-maker on defense.
And Soliai is the team's best run defender.
And the good news for the Dolphins is that Wake has a chance to play this weekend, same for Patterson and Soliai should be back at 100 percent by now.
Now, middle linebacker Dannell Ellerbe is dealing with a shoulder injury, but he's not expected to be a long-term issue, so before long the Dolphins should be back at full strength on defense.
And then we can see whether it was correct to expect the defense to be a major strength.
If it turns out to be just that, then the Dolphins' chances of making a return to the playoffs will greatly increase.