Dallas Cowboys are looking to put a stop to woes on defense

The question would be unthinkable in years past, particularly in light of the rich history of this NFL team. Still, it’s appropriate now:

Is there a D in Dallas?

There certainly wasn’t last season, when the Cowboys surrendered a franchise-high 6,645 yards, the third-most in NFL history.

“It’s definitely embarrassing, especially when you know the type of talent you have on the team,” cornerback Morris Claiborne said Friday at Cowboys training camp in Oxnard. “But it’s just not showing up.”

Making matters worse, the three best defensive players from last season are gone. DeMarcus Ware, the club’s career sacks leader, was released in March and is now in Denver; defensive end Jason Hatcher, who led the team in sacks last season, left for Washington in free agency, and linebacker Sean Lee is out for the season after suffering a torn knee ligament in the first off-season workout.

Otherwise, the Cowboys have the same top three cornerbacks from last season, and the same top three safeties. They signed defensive tackle Henry Melton, coming off a knee injury, and they moved up in the second round to draft defensive end DeMarcus Lawrence, but they’re largely relying on an underwhelming cast to generate a pass rush and help their defense flip a U-turn.

This comes at a time when NFL teams are putting up staggering offensive numbers, and when the Super Bowl champion Seattle Seahawks showed the true value of a smothering defense.

The Cowboys have made one significant change, replacing defensive coordinator Monte Kiffin with Rod Marinelli, last season’s defensive line coach. Too often last season, Kiffin was asleep at the switch, failing to make the necessary adjustments to neutralize offenses — although with that personnel, those adjustments might not have helped much anyway.

Marinelli provides a glimmer of hope, but the Cowboys would be hard-pressed to make the kind of defensive reversal the New Orleans Saints did last season, when they went from the NFL’s all-time worst in 2012 to allowing the fourth-fewest yards in 2013.

“We’re focused on us,” Cowboys Coach Jason Garrett said when asked about the New Orleans comparison. “We made some hard decisions in our organization with some guys who had been very good players for us. You think about DeMarcus Ware and the kind of career he had.

“We had to make some of those decisions, which are hard. The positive part is we have a younger team, way younger than it was three years ago. We think that’s a good thing. It shows up on our defensive line. We’re going to give a lot of players a chance to show what they can do.”

Before 2013, no defense had allowed more than three 400-yard passers in a season. Last year’s Cowboys gave up four such performances, and it would have been five had the Saints not taken their foot off the gas during a 49-17 rout. Drew Brees threw for 392 yards but the Saints rarely passed in the fourth quarter.

Even though their defense was horrendous, the Cowboys still came within a Week 17 loss to Philadelphia of making the playoffs. The unpredictability of the NFC East weighs heavily in their favor.

Overall, the Cowboys have been the definition of mediocrity. They have gone 8-8 three seasons in a row and are 136-136 dating to 1997, with just one playoff victory in those 16 years.

Dallas has offensive punch in quarterback Tony Romo — who has yet to prove he has anything more than warning-track power when it comes to the postseason — receiver Dez Bryant, running back DeMarco Murray, and reliable but well-worn tight end Jason Witten. The Cowboys averaged 27.4 points per game last season, fifth-best in the league.

As important as it is to score points, that doesn’t matter if you can’t stop anyone. The future of Garrett, in the final year of his contract, hinges on Dallas both scoring and stopping.

For his part, Cowboys owner Jerry Jones is looking to manage expectations. At his pre-camp State-of-the-Cowboys news conference, he intentionally steered clear of Super Bowl talk, a departure from years past.

“We’ve never had more new faces, yet have the optimism that I have for those new faces, many of them are experienced veterans to some degree,” Jones said. “Certainly, we’ve got our share of rookies and rookie free agents, but still, I’m very optimistic that we have a team that can come together ...

“It’s not about next year. We’ve gone from possibly being one of the older teams to being one of the younger teams, but I think we’ve got the fundamentals to compete and compete right now.”

That starts with defense. Barring a miraculous turnaround, this yardage-yielding unit could redefine doomsday.

Follow Sam Farmer on Twitter @LATimesfarmer