Kirk Cousins has a way of wincing when he smiles, as if even happiness has been hard-earned.

His isn’t the megawatt smile of a sporting hero born for the spotlight. It’s a working man’s smile, the look of a man who, even amid success, is keenly aware of how far he has still to go. As if to say: “I can get better. I can do better next time.”

Outside of his Western Michigan home town of Holland — population 33,000 — and Michigan State’s passionate fan base, Cousins had never been anyone’s hero.

His arrival in Washington was barely noted; he was cast as a career backup the moment the Washington Redskins chose him in the fourth round of the 2012 NFL draft. Until this season, when he supplanted Robert Griffin III as the starting quarterback, Cousins’s limited game-day appearances only cemented a reputation for committing costly errors at catastrophic times.

But over the past 10 weeks, the former backup has led the Redskins to a stunning turnabout, following up a 2-4 start with a 7-3 finish that clinched Washington’s first NFC East championship since 2012 and a first-round playoff date with the Green Bay Packers on Sunday at FedEx Field.

Master Tesfatsion, one of The Washington Post's Redskins reporters, breaks down the team’s playoff matchup against the Green Bay Packers. (Thomas Johnson/The Washington Post)

Cousins was near flawless in that stretch, throwing 23 touchdowns to three interceptions while setting a team record for passing yards in a single season with 4,166. Cousins credited the achievement to Coach Jay Gruden and his staff, as well as his cadre of gifted receivers, stout protection from the team’s young offensive line and every other player who suited up in burgundy and gold.

How did the 27-year-old Cousins, who this time last year was the Redskins’ No. 3 quarterback, become the linchpin of Washington’s improbable success?

Those who have watched him work up close see nothing improbable about it.

Day in and day out

Mike Shanahan, the former Redskins coach so instrumental in the Hall of Fame careers of quarterbacks John Elway and Steve Young, enumerated the tangibles that initially struck him about Cousins: the arm strength, his accuracy, the array of throws in his repertoire, courage to stand and deliver the ball in the face of onrushing tacklers and the smarts to decode defenses. Shanahan was the one who drafted Cousins, three rounds after Griffin.

But intangibles make a capable quarterback truly special, Shanahan noted.

“It’s very hard for people to see from the outside how somebody practices and goes about their business,” Shanahan said. “[Cousins] was a guy that, number one, was very accountable. Very passionate about the game, down to the little details. Late in the evening, he’d be the guy in the office by himself, looking at game film. It’s not talk; he did it day in, day out. Whether he got the opportunity to go in, he was going to be prepared.”

Cousins’s study habits and meticulous attention to detail, traits that Gruden, with obvious admiration, describes as “almost anal,” only intensified over the past two years as he sought new ways to become a better player.

Kirk Cousins, Trent Williams and the Redskins have had plenty to celebrate over the past 10 games, of which Washington has won seven while its quarterback has passed for 23 touchdowns and just three interceptions. (John McDonnell/The Washington Post)

In addition to practice, meetings and weight-room sessions at Redskins Park, Cousins works with a private throwing coach in the offseason. To improve his overall fitness, he also works six days a week with a personal trainer, whether in Northern Virginia or Atlanta, his wife’s home town.

“He came in by himself, sat on the couch and said, ‘I’m probably the worst athlete on the team,’ ” Pat McCloskey, director of training at One To One Fitness in Tysons Corner, recounted of their first conversation in 2014. “He wanted his body and athletic performance to be as efficient and effective as possible. He said, ‘If you direct me as to what to do, I’ll do the best I can and I’ll do it every day.’ ”

So they launched into a program of dynamic jumps, stretching and resistance work to improve his balance, agility and quickness — which Cousins showed off in his 13-yard dash past Buffalo defenders on Dec. 20 for his fifth rushing touchdown of the season.

He also sees a chiropractor and applied kinesiologist weekly and uses a computer-based form of brain training, devised by Michigan-based Neurocore, to sharpen his decision-making under pressure. And he grinds while on vacation, too, calling a local high school while visiting relatives in Fort Myers, Fla., last February for permission to use the Estero Wildcats’ field and borrow a handful of the team’s receivers for passing practice.

To improve his time management, Cousins devised a spreadsheet while vying for the starting job in late August that spells out each day’s activity in 15-minute, color-coded blocks. He still follows it faithfully.

“There is no entitlement in the NFL,” Cousins said. “You’ve got to prove it every day. Even Tom Brady had to compete; he had to earn his spot, day in and day out, year in and year out. So I just felt like I’ll keep competing and showing what I could potentially do, and let [the Redskins] do what they want to do.”

He put the work in

Time and experience on the job, more than anything, have been the kindling that ignited Cousins’s hot streak.

This is how oak trees begin. As saplings, they establish their roots underground before developing above it.

But NFL fans don’t have the patience of gardeners. To say Redskins fans have been slow to embrace Cousins is an understatement. Even his advocates could do no better than argue that he was the “least-bad option” when Gruden named him the starter for 2015 on Aug. 31, unwittingly triggering an anti-Cousins backlash by benching Griffin.

In doing so, Gruden tied his fortunes, as a second-year NFL coach with just four victories to his credit, to those of Cousins. And the two seemed to be sinking like stones after a 34-20 loss at the New York Jets on Oct. 18, in which Cousins threw two interceptions, bringing the Redskins’ record to 2-4.

With a petition circulating for Gruden’s ouster and Cousins’s benching, the coach summoned his quarterback for a closed-door meeting during the bye week that followed their seventh game.

What took place wasn’t a tongue-lashing. It was a film session, with Gruden seizing what might be called “a teachable moment” amid the potential wreckage of their NFL careers. He turned on a video of New England’s victory over the Jets that week, and together they dissected what Brady did.

Arguably the greatest to play the position, the Patriots quarterback didn’t make any throw Cousins couldn’t. He simply made smart decisions. He managed the game. He got the ball to more athletic teammates. He didn’t don a superhero’s cape, save the day or win the game on his own.

The lesson, a bit of a paradox, was two-fold: The Redskins were Cousins’s team, as Gruden had told Cousins and the world two months earlier, hoping to convey a season-long commitment through whatever rocky times were in store. But the Redskins’ success didn’t hinge solely on him. Cousins, the compulsively accountable quarterback who was determined to make everything right, didn’t have to single-handedly make anything happen or fix everything that went wrong.

“It doesn’t take anything special or anything magical to be a great quarterback,” Cousins said, recounting his takeaway that day. “You just have to be decisive. Have good command. Let the system work for you. Let the guys around you work for you. If you do that, good things will happen.”

Trust the process

The lesson proved alchemic, marking a transformation in Cousins’s performance.

It also fed into a mantra Redskins offensive coordinator Sean McVay had been preaching, drawn from the book “The Score Takes Care of Itself ” by the late Bill Walsh, who led San Francisco to three Super Bowl titles in a Hall of Fame coaching career.

“Trust the process, not results,” McVay said, distilling the message. And Cousins embraced it, sharing his coordinator’s conviction in the power of routine and detail.

Cousins had a favorite Walsh mantra of his own: “The accumulation of knowledge is a powerful thing.”

The two ideas — along with a verse from Proverbs that concludes, He will direct thy steps — convinced Cousins he was progressing, even if the results to that point suggested otherwise.

McVay never doubted.

Throughout the regular season, they met each Friday afternoon to review the roughly 100 pass plays in the mix for the upcoming game. Cousins didn’t simply report for the meeting with an understanding of his role in each play; rather he’d devised two or three variations on what he should do if something went awry or the defense countered with an unexpected move.

“He was thinking through all these different scenarios, because inevitably something’s going to come up that surprises you, to give him a chance to react,” McVay said. “He’s doing a great job of playing the game before the game.”

Cousins’s growing command of the offense coincided with speedy wide receiver DeSean Jackson’s return from injury, which gave him a deep threat. Jackson complemented the enviable talent of the passing targets already at his disposal, including linebacker-tough Pierre Garcon and 6-foot-3, 237-pound tight end Jordan Reed, who set a single-season team record for catches at his position, with 87. With Gruden and McVay calling more aggressive plays early in games, the Redskins closed with four consecutive victories.

“He’s just a more confident person in his job,” Reed said of Cousins. “I think that comes with reps and reps — and trust in the coaches. He’s out there playing ball; he’s not out there worrying about being benched.”

Respected by teammates and appreciated by his coaches, Cousins, whose contract is up at the end of this season, stands to be handsomely compensated next year, whether by the Redskins or another team.

He has become a coveted commodity, given the dearth of quality quarterbacks in the NFL. And his now-famous triumphal outburst after leading a comeback from down 24-0 against Tampa Bay — “You Like That?!”— will be emblazoned on rally towels mass-produced for Sunday’s playoff game.

But Cousins’s No. 8 jersey will be far from ubiquitous at FedEx Field. The team’s 16th starting quarterback in the past 16 years — and the first since 2009 to play all 16 regular season games — he is not yet beloved in his NFL home town.

So if the Redskins’ faithful want to see a bit more staying power before throwing their arm around Cousins, that’s fine.

Kirk Cousins will keep working, whether embraced or not. He has a plan for getting better each game, each NFL season.

And he has a schedule to keep.