Will Compton, left, and the Redskins defense say they have to be better at red-zone defense, third-down defense and at creating takeaways to make a push from 6-5-1 to the playoffs. (John McDonnell/The Washington Post)

During the two-game skid that has knocked the Washington Redskins out of the division race and NFC playoff position, shaky defense has been the main culprit.

The unit has held an optimistic outlook through its season-long struggles, but time may be running out. Yet defensive coordinator Joe Barry kept a broad perspective about what has ailed Washington’s defense during his weekly news conference Thursday.

“The number one statistic that we preach and that I’m really ultimately concerned with, the only stat that matters, is the scoreboard,” Barry said. “And as long as we hold our opponent to one point less than we score, that’s the only stat that matters.”

Washington’s defense hasn’t accomplished that over the past two games, nor has it achieved the other objectives it aims for every week. The Redskins will need that to change over the next four games as they attempt to make the playoffs for the second consecutive season with a strong finish in December.

Redskins defensive coordinator Joe Barry, right, says having allowed one fewer point than the team has scored is the only stat that matters. (John McDonnell/The Washington Post)

Linebacker Will Compton said the defense wants to limit opponents to 17 points, although only four teams allow fewer than 17.5 points per game. Washington has accomplished that once this season, against the Baltimore Ravens. The Redskins are 20th in the league, allowing 24.6 points per game. In the four games since the bye week, they have allowed 26.5 points per game.

Washington went 2-2 in those games despite an offense averaging 29.25 points.

“Even though we preach specific goals for every specific situation, again, like I said, the number one goal — the number one statistic — is to make sure when you look up, when it’s 0:00 on the clock, that they have one less point than we have,” Barry said. “And that hasn’t been good enough for the last two weeks because we’ve lost.”

The most glaring concern has been third-down defense, a category in which the Redskins are worst in the NFL at 48 percent. Barry said the team’s goal is to allow opponents to convert no more than 35 percent, which would rank fourth in the league.

The Redskins haven’t been close to reaching that over the past two games, allowing the Dallas Cowboys and Arizona Cardinals to convert 58.3 percent (14 of 24) of their third downs.

“It’s very situational football,” Compton said. “It’s just [about] taking care of us because we know we, as a defense, have been losing these past couple games. We’ve lost them. We’ve got guys with chips on their shoulders. We know that. We know we feel the pressure, but we know it starts with, hey, we need to stay unified. Whatever we’ve got to do to get a win, and we’ve got to win these games because it starts with us. And we know that.”

Beyond third downs, Redskins Coach Jay Gruden hasn’t been pleased with the defense’s lack of takeaways or red-zone defense over the past few weeks. Washington has won the turnover battle just once in the past four games, with a turnover differential of zero in that span. Gruden said the Redskins want to be plus-two each game. The team is tied for 19th with a minus-one turnover differential. The offense is tied for the 12th-fewest giveaways (14), while the defense is tied for the ninth-fewest on its side of the ball (13).

The defense in the red zone has been just as ineffective. Gruden said he would be satisfied if Washington’s red-zone defense was around 62 percent. The Redskins have allowed their past four opponents to score touchdowns on 76.9 percent (10 of 13) of their red-zone opportunities.

“Those are the key facets of winning football games and playing winning defense,” Gruden said of third-down defense, red-zone defense and creating turnovers. “We’ve been lacking in all three of those categories as of late, but we feel confident we can turn a corner and do a better job in all three.”

There are areas in which the Redskins have accomplished some of their objectives. They haven’t allowed a 100-yard rusher in the past four games, although Cowboys rookie running back Ezekiel Elliott and Cardinals running back David Johnson averaged 4.9 and 4.7 yards per carry, respectively. The Redskins are tied for the seventh-most sacks (30) in the NFL after finishing 14th (38) last season.

Still, the defense hasn’t done enough. It has four games to figure it out, or else this unit will be a significant reason the Redskins won’t play a game beyond Week 17.

“We have it,” defensive end Ricky Jean Francois said. “We get people’s mind-set to change over because these next four games is going to be able to [get] you the fifth seed, the sixth seed or you’re going to be home watching [the playoffs] on the big screen while you eat wings and sitting on your couch when you know you should’ve been in the playoffs. Everybody knows what’s on the line. I’m not going to say it’s a code-red situation; I’m not going to say it’s a panic situation. [All] we need to do is play Redskin football.”