Cowboys can sustain success on D

— -- Back in August, when the available evidence suggested the Dallas Cowboys could be historically bad on defense, I wondered whether the second-string units for teams such as San Francisco might be better. The Cowboys had lost DeMarcus Ware and Sean Lee from a 2013 defense that ranked as one of the league's five worst by just about any valid measure. They had no impact players.

The picture looks quite different now that the Cowboys have a 5-1 record and are coming off a 30-23 road victory over the defending Super Bowl champion Seattle Seahawks. The Cowboys rank near the bottom in defensive categories such as yards per play and sack rate, but they also rank among the top 10 in points allowed, interception rate, first downs per game, passer rating and Total QBR.

This Dallas defense is not terrible. It's been more asset than liability to this point, helping the Cowboys play complementary football while becoming one of the surprise stories in the NFL through Week 6. What's been the key for this Dallas defense and can the Cowboys keep this up? I've collected answers from league insiders, including some whose teams have faced Dallas, and identified a few reasons why it looks like the Cowboys' defense can continue to play well.

1. The Cowboys found a perfect match when they paired Rod Marinelli's personality with the questionable defensive personnel on hand.

A former NFL head coach noted recently that he thought the Cowboys' defense was playing as hard as any in the league. That was before Dallas went into Seattle and shut down Russell Wilson. A general manager I spoke with this week said Marinelli's promotion to defensive coordinator from line coach is looking like the catalyst for the Cowboys' defensive improvements.

"Dallas is playing better than I ever thought they would play on defense," the GM said. "They have matched the coach with the personnel. They have paired a bunch of lunch-bucket guys on defense with a lunch-bucket coach and it is working. They are playing with a lot of confidence. They have an edge. Right now they are playing with a chip on their shoulder because everyone told them how [bad] they were going to be and their coach is not allowing them to take that cop-out. It is the perfect marriage."

Another personnel evaluator used the term "try-hard guy" to describe both starting defensive ends -- Tyrone Crawford and Jeremy Mincey. He called defensive tackle Henry Melton an effort player known more for finesse than power. Marinelli's message has apparently resonated. It helps, too, that the scheme is relatively simple and has carried over from the previous season, making it easier for players to cut loose without thinking as much.

2. A philosophical shift on offense is taking pressure off the defense.

The Cowboys' ball-control offense has helped Dallas hold possession for an average of 34:42 per game, by far the highest number for the team during the Tony Romo era. Other Romo-era bests: 6.3 plays per drive, 37.5 yards per drive, 78.1 percent of drives with at least one first down, 56.3 percent conversion rate on third down. Dallas is running the ball 68.7 percent of the time on first down, the Cowboys' highest rate during the Romo era by more than 10 percentage points.

Every team benefits from an offense that can sustain drives. A team with questionable personnel on defense would need its offense to succeed even more.

"They completely controlled the clock against Seattle," a personnel evaluator said. "They finally found the right identity on offense. They have muscle on the line, they have a good back and they are not forcing Romo to win the game every week. They have turned him into more of a manager of the game. He can make plays, but you are not relying on him all the time. It is DeMarco Murray's team. This is the first year they have bought into the philosophy of pounding the ball."

3. Some individuals on the defense are playing much better than anticipated.

A personnel director who has studied the Cowboys pointed to Crawford, cornerback Orlando Scandrick and linebacker Rolando McClain as the best players on the defense right now. Pro Football Focus has Crawford sixth among 4-3 defensive ends in cumulative play-by-play grading through Week 6. Scandrick is the fifth-rated corner. McClain is third among inside linebackers.

Last season, Ware was the only Cowboy ranked among the top 27 4-3 defensive ends. Scandrick was 38th among cornerbacks, the best for any corner on the team. McClain was out of football.

A veteran offensive lineman who faced the Cowboys this season said he thought the Dallas defense was playing better as a whole than the talent of the individual players would normally allow. He said the way Dallas moved around its linemen made it tougher for an offensive line to come off the ball aggressively. "I was really impressed with how they played," the lineman said.

4. There are no signs of a defensive collapse looming.

Fortunes turn quickly in the NFL, but there is no reason to expect the Cowboys to stop playing with the effort and ferocity they have displayed on defense to this point. There is no reason for Dallas to change its offensive approach in a way that would compromise the defense.

The Cowboys should not need their defense to rank among the very best. Continued complementary play is a reasonable goal for a team with a physical offensive line that can control games as long as the coaching staff sticks to its revised philosophy. Depth is a concern, so attrition over the course of the season could hurt, perhaps more than it would other teams. But outside of that, there are no warning signs saying that the Dallas defense can't keep up this level of play.

Notes

New York Giants season becomes another roller-coaster ride, the team might not be changing as much as its schedule is changing. The Giants' three victories this season came against teams that have losing records against the rest of their schedules. The Giants' three defeats came against teams with winning records against other opponents. Keep that in mind when projecting how the Giants might fare over their next five games. They face 5-1 Dallas, 4-2 Indianapolis, 3-2 Seattle, 4-2 San Francisco and 5-1 Dallas (again) over that stretch.