Pittsburgh Steelers’ Cameron Heyward (C), Stephon Tuitt (R) and James Harrison.

By Sam Farmer/Los Angeles Times

Once the backbone of a proud NFL franchise, Pittsburgh’s defence had grown grayer, creakier, and slow as ketchup from a bottle.
Although they had the league’s top-ranked defense in 2011 and ‘12 - par for the course for a franchise that produced Mean Joe Greene, Jack Lambert and Mel Blount -- the Steelers slipped from 13th in yards allowed in 2013 to 18th last season. It was their worst defensive ranking since finishing 22nd in 1991, Chuck Noll’s final season.
Call it a Stale Curtain.
“If you play for Pittsburgh, you’ve got to be in the top 10 - top five, really,” safety Will Allen said.
“It’s the standard. You come here knowing that, and you’ve got to play up to that level. The fans want what they want, and we’ve got to deliver.”
While the defense has struggled, the offense has flourished. The 2014 Steelers set franchise records for points, total yards, yards passing per game and first downs in a season.
Receiver Antonio Brown was so good, he was at Warner Bros. studios this summer, making a diving, one-handed catch for NBC’s “Sunday Night Football” intro.
But a Pittsburgh team that’s all offense, with a defense that’s as gentle and welcoming as a cardigan-clad Mr. Rogers? Even that easygoing local icon would be ruffled about the recent decline. So the Steelers made changes. They parted ways in January with legendary defensive coordinator Dick LeBeau, who is 77 and had been flirting with retirement every year.
 The team promoted longtime linebackers coach Keith Butler to replace him. Butler was making a coordinator’s salary anyway, and the team was at risk of losing him to Arizona, Tennessee, Miami or any number of franchises courting him in recent years.
When LeBeau was coordinator, Steelers Coach Mike Tomlin respectfully steered clear of putting his stamp on the defense. Tomlin, who has a long history of working with Butler, is now more involved with the defense.
Pittsburgh’s defense no longer has its most recognizable player, Troy Polamalu. The wild-haired safety, among the best to play the position, retired in April after 12 seasons and eight Pro Bowls. It was reflective of the youth movement on the Steelers, who three weeks later used six of their eight draft picks on defensive players.
Three years in a row, the Steelers have used their first-round pick on a linebacker, selecting Jarvis Jones, Ryan Shazier and, this year, Bud Dupree. It’s a dramatic change for a franchise that has prided itself in finding great linebackers others have overlooked, the prime example being the undrafted James Harrison, a five-time Pro Bowl player still on the roster.
Before their recent run on the position, the Steelers had used their top pick on a linebacker only three times in the modern era, taking Lawrence Timmons in 2007, Huey Richardson in 1991 and Robin Cole in 1977. Under Butler, the Steelers’ defensive linemen have switched from a two-gap to a one-gap approach. In a two-gap scheme, a defensive lineman is responsible for covering the gaps on either side of his offensive counterpart. He engages the offensive lineman, reads which way the ball is going, then fills the proper gap. In a more aggressive one-gap scheme, the defensive lineman fires off the line of scrimmage and commits to a specific hole, penetrating the gap and, ideally, disrupting a play in the offensive backfield.
“In any sport, pride defines a team,” defensive end Cameron Heyward said. “Not in a sense of arrogance, but in a sense of, ‘We’ve got to put that stake down and say, They’re not crossing that line.’” Offenses had success running against the Steelers last season by stretching out plays laterally and creating wide lanes. Butler said the one-gap scheme will help curtail that because those penetrating defensive linemen should be able to get to the backs quicker.
What’s more, Butler said, the two-gap style makes it more difficult to get pressure on quarterbacks.
“A lot of people were blocking us up, getting one-on-one with our corners, and beating us deep,” he said.
“So what we’re trying to do is keep the ball in front of us, give our corners a chance, and if the quarterback holds the ball too long we’ve got to hit him.”
The Steelers gave up 86 plays of 20 yards or more last season, ranking a cover-your-eyes 27th in that category.
“It was awkward last year,” defensive end Stephon Tuitt said.
“For the talent we have, we shouldn’t have been doing that. But the best thing about football is there’s a next year. You figure out the bad plays and you fix them. Now’s the time that we’re answering all those questions.”
And when they do?
As Mr. Rogers would say, it’s a beautiful day in the neighbourhood.