General Manager Scot McCloughan must figure out a fair contract for Kirk Cousins, but also focus on improving the Redskins’ defense. (Jonathan Newton/The Washington Post)

The confounding thing about the Washington Redskins’ breakthrough season is that they didn’t intend to win this way.

They wanted to rely on elbow grease: physical, aggressive defense and a power running game. Instead, they allowed the fifth-most yards per play (6.0) in the NFL and were tied for the third-fewest rushing yards per play (3.7).

They wanted to lessen their dependence on the quarterback. Instead, Kirk Cousins rose from backup to starter and set a franchise record with 4,166 passing yards.

They wanted to have a nice, quiet season under the radar. Instead, they overachieved and managed to make the masses care again.

It was an interesting path to respectability. They lost their directions and somehow traveled to a better place. As you audit the 2015 season and contemplate what it meant to Washington’s future, there are legitimate reasons to fear it was an accidental success.

1 of 36 Full Screen Autoplay Close Skip Ad × Top moments from Redskins-Packers playoff game View Photos Washington’s surprising season comes to an end with a 35-18 first-round loss to Aaron Rodgers and Green Bay. Caption Washington’s surprising season comes to an end with a 35-18 first-round loss to Aaron Rodgers and Green Bay. Jan. 10, 2015 Redskins quarterback Kirk Cousins (8) takes the field before Washington's first-round playoff game against the Green Bay Packers at FedEx Field. Toni L. Sandys/The Washington Post Buy Photo Wait 1 second to continue.

But there’s also this to ponder: The reason General Manager Scot McCloughan focused first on improving the team’s toughness, offensive line, defense and overall talent around the quarterback is because those are the easiest ways to get a rebuilding effort started. Even if those moves don’t produce immediate results, they establish the foundation for change, creating a blue-collar mentality and putting developmental pieces in place that can still help the team in smaller roles as those players grow.

[Steinberg: Sky is the limit for Redskins, except the future is never clear]

If McCloughan started by trying to fix the big things — quarterback, the passing game, acquiring elite playmakers — he would’ve had to wait for all that style to manifest itself through repetition and without a solid base of support. It would’ve been akin to putting fancy windows on a faulty structure, which is what the franchise had tried to do for most of this century.

Think about it that way, and the surprise manner in which Washington flourished can be deemed a welcome occurrence rather than reason to worry the team will be exposed as a fraud next season. It’s a bonus that Cousins took command, and the offense (or at least the passing game) thrived. It allows McCloughan to focus on what he does best and devote more resources to ensuring the spine of the team gets stronger.

Besides figuring out a fair contract for Cousins, McCloughan and the front office should commit most of the offseason to upgrading the talent on a defense that allowed 380.6 yards per game this season, which ranked 28th out of 32 NFL teams.

Despite changing defensive coordinators and turning over half of the starters from a year ago, the defense fell eight spots in total defense. The team tried to play a more attacking style, but it resulted in just two more sacks than the previous season. But the defense did allow fewer points, dropping from 27.4 points per game to 23.7.

[Redskins’ plan is to sign Cousins, part ways with RGIII]

Before you get carried away with criticism of the job Joe Barry did running the unit, you have to remember that this defense never took the field as projected. Cornerback Chris Culliver, McCloughan’s signing in free agency, was limited to six games. Junior Galette didn’t play a game. Five other starters missed multiple games. The expectations for the defense dipped all the way to amazement that players signed off the street could start games without incident.

Last offseason, McCloughan used free agency to find stopgap veterans to start the process of building a competitive defense. Washington looked professional, at least, with the likes of nose tackle Terrance Knighton and safety Dashon Goldson adding experience and winning habits. The draft was used more for the offense, with six of the 10 selections on that side of the ball, including five of the first six picks.

Despite making the playoffs and enjoying a few stellar defensive moments, Washington is desperate for youth, athleticism and speed in every portion of the defense. McCloughan will be searching for more players with talent like Preston Smith, the 2015 second-round pick who had eight sacks during his rookie season. And as good as Smith was in flashes, he needs to have the offseason of his life to improve his body and conditioning, which should help him become a more consistent player.

“I have to get better with a sense of urgency,” Smith said. “It’s a long season ahead, next season, and I now know what to expect. I know my rookie year is done, so I have to be a vet now in the locker room. It’s time to improve and take my game up another level and come back and do great things.”

McCloughan is a complete talent evaluator, but his greatest strength might be finding defensive players. He put together most of the core of the great defense that helped Jim Harbaugh thrive in San Francisco. He helped Pete Carroll and John Schneider build the NFL’s best defense in Seattle. McCloughan has consistently helped teams find late-round and undrafted defensive gems.

It’s realistic to think the front office can find the parts to improve the defense quickly without making shortsighted moves and overpaying in free agency. It’s possible to rise from the bottom of the league to the middle of the pack in one year by employing a bunch of hungry, unheralded athletes who play with great energy. The veterans have already set a standard for work ethic and camaraderie. The team is building upon the 28th-best defense in the league, but there’s more to these players than that awful statistic.

“It’s on us to go into the offseason and prepare like we’re a losing team,” said defensive end Jason Hatcher, 33, who is torn between playing another year and retiring. “Go in there like we haven’t been nothing and always remember this taste in our mouth.

“Always remember this going into the offseason, workouts, all of it. Always remember this moment and promise each other that we’re never going to let it happen again.”

Hatcher was speaking in the locker room minutes after Sunday’s 35-18 playoff loss to Green Bay. His passionate words resonated, but before the team concerns itself with playoff redemption, it must get back to the postseason.

To do that, Washington will have to win the way it originally intended. Fix the defense. Improve the run game, while you’re at it. Back to the elbow-grease approach.

It’s the first turn on the path to intentional success.