Two weeks ago, Real Salt Lake had the worst defense in the Western Conference. But since then, a few changes to the back line has solidified a unit that has allowed only one goal in its past three games, all wins, as RSL has surged to third in the West.

“I saw a total team defending,” RSL coach Mike Petke said after RSL’s 2-0 win over Seattle on Saturday, its second shutout of the Sounders in eight days, “and immediate counter pressure when we lost it in transition, which when we didn’t win the ball right away at least we forced them sideways or backwards.”

He stressed that the shutout couldn’t be attributed only to the back line, which is true. But in tandem with the team’s defensive shape improving, the back line has matured and found balance.

When RSL had made giving up multiple goals a habit on the road, it was easy to point the finger at RSL’s back line. Three of the four players defensively — right back Brooks Lennon, left back Pablo Ruiz and center back Nick Besler — were playing positions new to them.

Petke chose to use attacking players as outside backs — partially after a spate of injuries to incumbent starters Demar Phillips and Tony Beltran. But that left the team exposed at times as they learned their new roles.

That wasn’t the case Saturday.

“We knew how they were going to play,” left back Danilo Acosta said of Seattle. “Whenever [Will] Bruin came back they were going to try to play some long balls and get the second balls and overall, the guys handled it really well.”

Lennon, traditionally an attacking player, made his 12th straight start, and 11th in defense. The biggest transition for him was the defensive responsibilities, but at this point in the season it’s nothing new.

On the other side, Acosta earned his fourth start of the season. He was expected to be the regular starter at left back to start the season, but on Saturday Petke cited an inconsistency in Acosta’s effort as one of the reasons he began the season on the bench.

In Acosta’s first start of the year, a 3-0 win against Colorado, Petke subbed him out at halftime for a more attack-minded player in Ruiz. Acosta said he’s made improving the attacking aspect of his game a priority this year.

Between Lennon’s improving defense and Acosta’s improved attack, RSL out-shot Seattle 18-5. And a full-strength Houston team, the highest-scoring team in the West, was held to one goal on Wednesday.

“I would think [Acosta’s] overlapping and underlapping tonight, I don’t know who had more, him or Brooks,” Petke said Saturday. “Whereas usually it’s Brooks getting really attacking.”