The Patriots have had a tough time containing opponents, such as the Dolphins’ Ronnie Brown, on third downs and near the goal line this season.

The Providence Journal / Bob Breidenbach

The New England Patriots needed to win against the Miami Dolphins, and just like so many other times when they were in a crucial situation, they found a way to get the job done.

While the offense wasn’t perfect, it never truly is, as Bill Belichick would tell you, Matt Cassel & Co. did more than their fair share in the victory. That’s not to say that the defense didn’t pull its weight, or that New England won in spite of its defense. But there continue to be problems on that side of the ball that the Patriots will need correct as the season winds down to qualify for the playoffs.

Two of the more glaring issues: third down and inside the red zone. The Patriots are near the bottom of the league in both categories.

In Miami, the Dolphins converted half (6-of-12) of their third-down opportunities, including three during their second touchdown drive. On that possession, Chad Pennington completed a 15-yard pass to rookie Davone Bess on third-and-10, a 20-yard pass to a wide-open Greg Camarillo on third-and-12, and another 10-yard completion to Bess, this one on third-and-4 from the New England 20.

Two plays later, Pennington lowered his shoulder to meet Mike Vrabel and dove over the goal line.

As they’ve posted a 2-2 mark over their last four games, New England has allowed its opponents Indianapolis, Buffalo, the Jets and Dolphins to go a combined 26-for-49 (53 percent) on third downs.

For the season, the Pats’ mark of 44 percent is in the bottom fifth in the NFL; Baltimore and Tampa Bay lead the league at a stingy 32 percent.

San Francisco struggled against New England during their October loss, converting just one of nine opportunities; the Patriots won that game, 30-21. The next week, in San Diego, the Chargers were good on three of 10 chances. But as is well remembered, they didn’t need many third downs in that game, as they completed several deep bombs.

The blame for the numbers can’t all be placed on the secondary, but the unit has been an area of concern this season, as it has been in flux nearly since Day One.

Asante Samuel and nickelback Randall Gay departed in free agency, and Fernando Bryant didn’t work out as planned. Jason Webster has returned, but a protracted absence during training camp due to a hamstring injury that led to his being released in late August. Throw in season-ending injuries to Rodney Harrison, Tank Williams and Terrence Wheatley, plus Lewis Sanders’ hamstring troubles, and it’s easy to see why cohesion might be an issue.

Last year, as New England posted one of its best defensive efforts statistically in franchise history, it allowed opponents to convert on third down just over a third of the time (33.7 percent).

Certainly the entire defense must claim responsibility for the problems inside the 20.

After seeing Miami cross the goal line on three of five trips into the red zone Sunday, the Patriots have only stopped teams from scoring touchdowns on 13 of 34 opportunities, a success rate of more than 65 percent for the opposition.

That figure is one of the four worst in the league.

In their 11 games, they have prevented just one team from scoring a touchdown in a red-zone situation: the lowly Rams, who came away with two chip-shot field goals in their trips inside the 20-yard line. And St. Louis, like San Diego, had success with the long ball in that game.

On the other end of the spectrum, Miami was 4-for-4 in its September win over New England, and the Colts were 2-for-2 earlier this month.

With Cassel at the helm, the offense has performed better, particularly in recent weeks, than many outsiders had expected. For much of this decade, the strength of the Patriots has been their defense, but right now that unit needs to do some fine-tuning for New England’s wins to keep coming.

smanza@projo.com