ASHBURN, Va. -- One game did not make the Washington Redskins’ defense. One month might.

The Redskins opened with a dominant performance against the Arizona Cardinals, providing reason to believe that maybe after a decade of struggles, they finally have a good defense.

They can prove even more in the next month against four quarterbacks with 23 Pro Bowl berths between them: Andrew Luck, Aaron Rodgers, Drew Brees and Cam Newton.

If the Redskins can slow down that quartet, they could be on their way to doing something they haven't done since 2009: finish with a top-10 defense in either points or yards allowed. They haven’t finished in the top half in either category since 2011.

Sunday’s 24-6 victory at Arizona provided Washington’s defense with momentum, and not just because of their statistics.

“Everybody was on the same page as far as preparation,” Redskins linebacker Mason Foster said. “Guys were locked in to everything they had to do.”

Here’s why they feel good:

The line. When Jonathan Allen was lost for the season after five games in 2017, the defense took a big hit. They’ve added enough depth with rookies Daron Payne and Tim Settle to provide a buffer. On Sunday this group -- Matt Ioannidis is key here, too -- limited the Cardinals to 68 yards rushing; David Johnson had only 37. The Redskins sacked quarterback Sam Bradford just twice, but they rushed four defenders on 32 of his 36 dropbacks. That meant there were seven in coverage most of the game; Bradford, throwing quick passes, averaged 4.5 yards per attempt.

In the run game, Payne or Allen often shed blocks and made tackles after short gains, and in other instances they occupied multiple blockers so linebackers such as Foster or Zach Brown could.

“They were clogging up lanes,” Foster said. “The ball has to come out quick, so it helps in coverage. When I’m matched on certain receivers, I can trust them [in play-action] to close off the gap so I can focus more on coverage than having to dive down into the run.”

Their ball-control offense. The defense was helped by what the offense did: Control the ball for 38 minutes, eight seconds. The Redskins rushed for 182 yards and, perhaps, discovered an identity -- and that should have a trickle-down effect.

“Explosive to me is ball control, having big-play ability, of course, but also expressing your will on the defense,” Redskins coach Jay Gruden said in July. “Hopefully with the power we now have at running back and the tight ends able to block, I think we can control the line of scrimmage. So explosive might mean control the ball and score 20 points.”

Of the 17 teams that finished with an edge in time of possession last season, 12 won at least nine games. Of the top five teams in time of possession, four had defenses that ranked in the top five in yards allowed per game, and the other ranked seventh. And four of those teams ranked among the top seven in points allowed.

Communication in the secondary. They’ll be challenged by much better passing teams than Arizona. However, building blocks were evident. Two plays by cornerback Quinton Dunbar were telling. The first, on a third-and-5 in the first quarter, involved Dunbar and two other young defensive backs: corner Fabian Moreau and safety Montae Nicholson.

That group faced a bunch formation on the outside. They communicated pre-snap what to do and what routes to expect. At the snap, Moreau jammed the front man and prevented a possible pick route. Nicholson took the inside route and Dunbar had the outside receiver. Dunbar drove on his man as the ball arrived, limiting him to four yards.

“It’s one thing to identify what you’re gonna get done, but you’ve got to identify something that puts you in perfect position to make the play,” Dunbar said. “We studied all week what bunch routes we were getting.”

Late in the third quarter Dunbar, in his fourth season but first as a full-time starter, showed his growth at corner on an interception. It goes back to 2015, when he played a Cover 3 look properly but blew a chance at an interception by not playing with better vision, teammate DeAngelo Hall told him.

Flash ahead to Sunday. Once more in Cover 3, Dunbar kept his vision on the receiver and the quarterback. When he saw another receiver trying to hit an area he was vacating, and knowing where his safety help was, Dunbar charged to the open area and picked off an overthrow.

“That separates the good from the best,” Dunbar said. “To understand concepts and get out of your element and zone to go make a play in another zone is pretty good.”