Progress doesn’t always come on a schedule, yours or anybody else’s.

Mariners left fielder Dustin Ackley hit .273 in 90 games during his first season in 2011, even earning a Rookie of the Year vote. But his development has come in fits and starts since.

“He was the best college hitter in the draft,” Mariners manager Lloyd McClendon said. “…We’re in such a hurry to see guys develop, but sometimes it takes a while.

“I just think he’s turned a corner.”

Ackley delivered one of his best performances of the season Sunday afternoon at a time when the Mariners desperately needed the boost, hitting a go-ahead, three-run home run and knocking in a game-high four runs as Seattle defeated Washington 5-3 at Safeco Field.

The victory allowed the Mariners to avoid a three-game sweep against the National League leaders — and salvage some momentum ahead of a vital series in Oakland — a sweep that looked downright likely after another early-inning Nationals power surge.

In the second inning, Bryce Harper accepted the invitation of the Hit-It-Here Café with a 418-foot drive over the right-field fence and off the restaurant’s fortuitously shatterproof windows. He added another solo shot off Mariners starter Hisashi Iwakuma in the fourth, combining with Nate Schierholtz’s third-inning blast to take Washington’s weekend home-run total into double digits.

“They hit some homers early, and it could have been, well here we go again,” Ackley said.

But Iwakuma settled in. And Seattle (73-62) manufactured its first run in the bottom of the third.

Brad Miller led off with a double, Austin Jackson moved him to third on an infield single and Ackley brought Miller home on a hit-and-run through the gap Nats shortstop Ian Desmond had just vacated.

That same stretch of the order sparked another rally in the fifth.

Nine-hole hitter Miller, who finished 3 for 3, dropped a single into center and leadoff man Jackson followed with the second of his three hits.

“That kind of puts pressure on a pitcher right there,” Ackley said. “He didn’t pitch much out of the stretch today but I think when he did, he was more likely to make a mistake.”

Tanner Roark’s 2-0 pitch hung over the inside of the plate and Ackley hammered a high, looping shot into the right-field stands to give Seattle a 4-3 lead, one Iwakuma and a long list of relief pitchers never relinquished.

Fernando Rodney pitched around Harper’s leadoff single in the ninth to bring Seattle’s homestand to a victorious end.

The Mariners open September a half-game out of the second and final wild-card spot with 27 games remaining. They — and their left fielder — are where they need to be.

“Early on, when I got called up in 2011, it feels really similar to how I’m able to compete in the box and not have to worry about who’s on the mound or what I’m doing with my swing,” said Ackley, who has hit seven home runs in his past 28 games. “It’s just going up there and not thinking.

“I think that’s ultimately where I’ve wanted to be the whole time.”

AL wild card
Top two teams will play each other in a one-game playoff.
Team Record Gms back
Athletics 78-58
Tigers 74-62
Mariners 73-62 .5
Indians 70-64 3
Yankees 70-65 3.5
Blue Jays 69-67 5