To motivate a football team prone to wobbling during prime moments, Jay Gruden uses a pet phrase: Be a master of the situation. The Washington Redskins coach says it all the time. By now, his players probably can recite it backward.

Too often, they have acted as amateurs of the situation. Red-zone, third-down, end-of-game management — they can be so iffy in these critical, game-changing areas, which is why you have bitten your nails so much this season that they grow back already gnawed. That’s just what this team is at this point in its development: good and erratic.

There is one situation, however, that Washington has mastered. And to add to the shock factor, the defense — mocked weekly for the benevolence it shows opposing offenses — is the unit that can boast the mastery. When it comes to retaining a late-game lead, you can depend on the NFL’s 23rd-ranked defense to be an effective closer.

Washington proved it again Sunday during a 27-22 victory over Philadelphia at Lincoln Financial Field. In a tense and vicious game, it came down to the NFL’s worst third-down defense showing just enough resistance on the final drive against Eagles rookie quarterback Carson Wentz. It ended with linebacker Ryan Kerrigan beating a backup right tackle to toss Wentz and force a fumble that Trent Murphy chased down and landed on, ensuring another close victory for a team that seemingly knows no other way.

The Washington Post's Scott Allen and Keith McMillan break down the Redskin's win against the Philadelphia Eagles. The Redskins now have an estimated 59% chance of making the playoffs. (Elyse Samuels/The Washington Post)

It was the fifth time these Redskins have been in this situation, leading late and needing the defense to finish. The defense has a 4-1 record, losing only at Detroit, a game in which the veteran defensive players questioned coordinator Joe Barry’s conservative approach after quarterback Matthew Stafford shredded them. The other victories: at the New York Giants in Week 3, when rookie linebacker Su’a Cravens intercepted an Eli Manning pass; at Baltimore in Week 5, when Joe Flacco drove the Ravens within 21 yards of the end zone before throwing an incomplete pass on fourth and eight; and against Minnesota in Week 10, when Preston Smith sacked Sam Bradford to end the Vikings’ threat.

In addition, when Washington tied Cincinnati in London, the defense had to keep the game knotted twice, once in the fourth quarter and again late in overtime, and came through on both occasions.

You wouldn’t take this defense — that raggedy, underdeveloped, talent-deficient unit with a much-criticized coordinator — every day of the week. But when the clock strikes 4 p.m. on Sunday, it finishes like few defenses can.

Washington’s success in this area doesn’t absolve Barry from scrutiny, and it doesn’t diminish the need for General Manager Scot McCloughan to make some shrewd investments in the defense in the offseason. It does indicate, however, that something positive is being built. The weaknesses obstruct most of the good. But Washington has players on defense who will fight and who possess the toughness and belief that they can find a way, no matter how ugly they make it look.

What’s that worth? Good question. But the value isn’t zero.

“Your blood pressure, it is going through the roof,” defensive lineman Chris Baker said of clutch situations. “You are like, ‘Come on, someone just make a play. I have to make a play. Someone has to make a play.’ It was all of us out there, like, ‘Hey, we are not going to give up on defense again. We can’t do it three weeks in a row.’ ”

Washington (7-5-1) had lost the previous two games while playing plenty of poor second-half defense against Dallas and Arizona. It didn’t have a lead or tie to preserve, but it didn’t give the offense enough of a chance. That bothered the defensive players, the reality that they were hindering the team’s playoff hopes.

This performance was better. Still, it wasn’t anything worth pounding their chests over. Philadelphia held possession for 61 percent of the game. It converted 50 percent (9 of 18) of its third downs, even higher than the league-worst rate of 48 percent that Washington allows. The Eagles gained 383 yards, about 13 yards more than what Washington normally yields.

Washington wasn’t good. It was competitive, though. Consider that six of Philadelphia’s points came on Leodis McKelvin’s interception-return touchdown. That mistake was on Kirk Cousins. So the defense gave up just 16 points. The Eagles scored a touchdown just once in four red-zone tries. You might consider Washington a broken defense, but on this day, it bent without suffering any new fractures.

It actually achieved Barry’s gold standard of giving up fewer points than the opposition. And it did so while losing linebackers Will Compton and Cravens to injury. Safety Will Blackmon, who has been a starter at times, missed the game with a concussion.

“One thing about this team and this defense: We don’t give up,” cornerback Quinton Dunbar said. “Playing hard is never the issue. So we’re just trying to get it all together and mesh as one and peak-perform down the stretch.”

After Washington scored to take a 27-22 lead with 1:53 remaining, you couldn’t help but fear that the offense had left too much time for Philadelphia. You couldn’t help wondering whether Chris Thompson should have taken a knee shy of the end zone so that the offense could have exhausted more of the clock. But it was important for Washington to trust its defense. It was important to let the unit do what it does best.

On Sunday, there was evidence of lessons learned. Unlike in the Detroit loss, Barry alternated between soft coverages and bringing pressure on that final drive. The Eagles still drove from their own 25 to the Washington 14-yard line, so there were breakdowns. But that often happens when a defense is trying to close a game and it knows the opponent needs a touchdown. If a field goal could have beaten Washington, the defense would have had to play tighter. But it didn’t, so Washington could play safer at times. When it mattered most, Barry called a blitz to force an incomplete pass from Wentz with 26 seconds remaining. And on the next play, Kerrigan won the game.

“I was just back there in jubilation!” cornerback Josh Norman said of Kerrigan’s sack-fumble. “It was like, ‘Yes! Finally! . . . We can get up out of here and go home.’ ”

Prayers answered, situation mastered — again.