Former Steelers offensive coordinator Bruce Arians, left, watches practice with Mike Tomlin in 2010. Arians, who is now the coach of the Arizona Cardinals, insists he has nothing to prove in Sunday's game against the Steelers.

PITTSBURGH — Bruce Arians insists this isn’t about payback, that he has nothing to prove on Sunday when the Arizona Cardinals play at Heinz Field.

It’s their head coach’s first regular-season game in Pittsburgh since the Steelers sent their former offensive coordinator into a “retirement” nearly four years ago that lasted barely a week.

“I’ve been in that visitors’ locker room a number of times,” Arians said. “It won’t be totally new to me.”

Maybe, but the Cardinals (4-1) playing the role of heavyweight in a division that was supposed to be one of the toughest in the league? That is new territory. Arizona isn’t just winning games, it is dominating them. The Cardinals have outscored opponents by 100 points through five weeks, the highest differential over that span since the Patriots during their unbeaten regular season in 2007.

It’s lofty territory for the franchise if not necessarily some of the principals involved.

The Cardinals’ roster and staff is littered with former Steelers who have a Super Bowl ring stashed away somewhere, from Arians to assistant head coach Tom Moore to inside linebackers coach Larry Foote to outside linebacker LaMarr Woodley.

Hey, they don’t call the Cardinals “Pittsburgh West” for nothing. Or maybe the Steelers are “Arizona East.”

Considering the connections between two franchises 2,000 miles apart in geography but near mirror images of each other in terms of philosophy, you’re probably good either way.

The Arizona offense that Steelers coach Mike Tomlin sees on tape looks a lot like the one Arians guided during his eight years calling the plays in Pittsburgh. When Arians looks at film of the Steelers’ reinvigorated defense, Tomlin’s fingerprint smudges are unmistakable.

There are few secrets between two teams that only play each other once every presidential cycle. Arians and Steelers quarterback Ben Roethlisberger remain close. Cardinals wide receiver Larry Fitzgerald praised Pittsburgh’s offensive coordinator for always being able to “get the best out of me” when Todd Haley was calling the plays during the team’s breakthrough postseason run in 2008, a run that ended with a loss to Arians and the Steelers in the Super Bowl.

Arizona certainly seems headed back in that direction.

The last six teams with a point differential in triple digits through five weeks all played in the final game of the season, with four of them holding the Lombardi Trophy.