With their 24-10 victory over the Arizona Cardinals Sunday night, the Washington Redskins finally got four solid quarters out of their talented defense. The turnabout -- though the unit remains last among the NFL's 31 teams -- was attributable to several factors.

Among them, the defense:

Got its best game yet from tackle Dan Wilkinson, who occupied blockers, enabling the linebackers to make more plays, and kept the pressure on quarterbacks Jake Plummer and Dave Brown.

Committed fewer mental errors among the linebacking corps and paid greater attention to detail overall. The crisper play was reinforced by film study during the bye week of the defense's worst plays this season. Players dubbed it "negative video." But it had a positive effect, according to defensive coordinator Mike Nolan.

Played with spirit throughout. The defense's resolve seemed to strengthen as the game unfolded, sparked in the first quarter by the offense's struggles and in the second quarter by the first of Champ Bailey's three interceptions, which he returned 59 yards for a touchdown that gave Washington a 10-3 lead.

While defensive specialist Bill Arnsparger insisted he did little more than stress fundamentals since being hired last week to help the struggling unit, Hall of Fame linebacker Sam Huff saw subtle shifts in the defense's approach against Arizona that he attributes to the counsel of an experienced, dispassionate observer.

"Whatever Bill Arnsparger is, is help," said Huff, who provides color commentary for the Redskins' radio broadcasts. "You need somebody that has been there, worked there and has some age on him. I think a lot of credit has to be given to the ownership of this football team for being willing to make changes even though his team was winning. There is a big change in attitude. And credit has to be given to [Coach] Norv Turner, to say, `We need help. We need a consultant.' "

The Cardinals' offense, of course, played a role in its own unraveling. Arizona has neither a running back with the explosive ability of Carolina's Tshimanga Biakabutuka nor a quarterback with the timing and accuracy of Dallas's Troy Aikman.

Sunday against Washington, a team they swept last season, the Cardinals managed just 274 yards of offense, including 67 yards rushing (3.4 yards per carry).

Just 20 of the 43 passes (46.5 percent) thrown by Plummer and Brown, who took over after Plummer broke the ring finger on his throwing hand in the third quarter, were completed. Half the Cardinals' drives (7 of 14) were limited to three plays and a punt. The Cardinals converted only 25 percent (4 of 16) of their third downs.

For a Redskins defense that had been surrendering 433.5 yards of offense per outing, such anemic Cardinals statistics suggest that improving the defense's play isn't so much a matter of bringing in new players as it is staying the course.

A more telling measure of the defense's progress will be delivered Sunday, when the Redskins, whose 4-1 record puts them atop the NFC East, travel to Dallas for the season's second meeting with the Cowboys (3-2).

Against Arizona, Huff said he saw the defensive adjustments he had hoped the Redskins would make earlier in the year -- including leaving Wilkinson in the game on more third downs. Wilkinson has been taken out in certain situations while pass rusher Ndukwe Kalu comes in for Kenard Lang at defensive end and Lang slides to tackle.

"When you take a ballplayer out of the game like Big Daddy, you're taking out the pressure man from the middle," Huff said. "Big Daddy will say, `I got into a rhythm,' but he got in a rhythm because he stayed in the game."

Nolan, however, said it was largely perception that Wilkinson played more. He stayed in after Kalu went down with a broken foot late in the fourth quarter. "Dan's good play was his own performance," Nolan said. "He did an excellent job tying up blockers."

Coaches had said early in the season they planned to substitute for Wilkinson on passing situations, partly to give him rest. Wilkinson played more snaps than any other defensive tackle in the NFL last season. But he showed no signs of fatigue Sunday, sacking Plummer, making two solo tackles and one tackle for a loss and getting nine quarterback pressures.

The game was also the best linebacker Shawn Barber has had. Huff, who thinks Barber has played better than he has received credit for, said the linebackers were more effective because they played a step closer to the line of scrimmage. "Football players have to be put in a position to make the plays, and this is what Bill Arnsparger, in my opinion, did: He placed the linebackers in position to make plays," Huff said.

Nolan played down the shift in the way the linebackers lined up.

"The backers played better because they cut their mental errors in half," he said. "There was some simplification of what we did. When you have a lot of young guys, the smallest of things can throw them off somewhat. In essence, we had a lot of people around the ball."

Barber's big play was his third-quarter sack of Plummer, whose finger was broken when it got snared inside Barber's face mask. It was a clean hit and dropped Plummer for a seven-yard loss, ending the offensive series.

With all three starting linebackers in new roles this season, that's where the Redskins' defense likely can make the biggest improvement in coming weeks. Turner said he was particularly pleased with Barber's play and that the defense didn't give up a big play.

So the existing personnel, in short, should be able to do the job.

The defensive line is better at each position than it was a year ago. Defensive end Marco Coleman is a dramatic upgrade; Lang is far more active and effective than a year ago; and Wilkinson and Dana Stubblefield are playing in better sync and shape than before.

At cornerback, 17-year veteran Darrell Green needs virtually no coaching, while Bailey is picking up the pro game quickly, though Arnsparger sees spots where he can improve his technique.

"Other receivers study him; well, he's got to study them," Arnsparger said. "He's got to continue to do that. There's nothing magical. There's no mystery about it."

At free safety, Sam Shade is far superior to Stanley Richard, as is Leomont Evans to last year's strong safety, Jesse Campbell.

The group started strong against Arizona, holding the Cardinals to three plays and a punt on their first series. The Cardinals came back to drive 52 yards and take a 3-0 lead on a 44-yard field goal. The Redskins had tied the score at 3, though the offense still wasn't running smoothly, when Bailey grabbed the interception and returned it for a touchdown with roughly four minutes left in the first half.

"That was a big turning point in the ballgame," Cardinals Coach Vince Tobin said.

Overall, both Nolan and Arnsparger were pleased, but aware that another test waits in Dallas.

"I thought we carried out our assignments, and we did it aggressively," Arnsparger said. "We have to continue to get better. It's important that we go back to stress basics: lining up right, knowing our assignments, and tackling and making things happen. We did that, and that's what we have to continue to do."