ORCHARD PARK, N.Y. — Josh Allen was 8 years old when he marveled at how then-Steelers rookie quarterback Ben Roethlisberger ably shed tackles and eluded charging defenders before completing passes from awkward stances and angles.

“Watching his game back in the day, the play was never over with him,” Allen recalled this week as Buffalo prepares to open its season hosting Big Ben and the Steelers on Sunday.

“He’s able to find ways to escape and get the ball out in some funky ways,” the Bills quarterback added. “He’s never had a play given up on him, and he’s never given up on a play.”

Allen won’t dispute how his description of Roethlisberger compares to his own strong-armed and mobile attributes, which he displayed in his only preseason appearance by bursting out of the pocket and throwing across his body to hit Cole Beasley against Green Bay.

“I think it’s more than I ever realized as a kid ... I see the comparisons of where we’re at physically,” he said. “But that’s a Hall of Fame quarterback. And I’ve got some time to go before we get into that conversation.”

For everything Allen accomplished last year in setting numerous single-season franchise passing and scoring records, he faces the challenge of maintaining his production entering his fourth season.

At 39, Roethlisberger is a two-time Super Bowl champion with a long-established reputation of success, reflected in the Steelers’ run of stability. Pittsburgh’s never experienced a losing season during his 17 seasons behind center.

Mike Tomlin noted as much when asked how he has benefited from having just one quarterback during his 15 seasons as Steelers coach.

“I don’t know the alternative, to be honest with you. Obviously, continuity is an asset,” Tomlin said.

“But it’s very similar to the traction (Bills coach Sean) McDermott and Josh Allen are gaining up there,” he added. “Every day spent together facing the challenges that this game provides us all, I think there’s collective growth in that. There’s cohesion in that.”

While set at quarterback, Pittsburgh unveils a new-look offense under coordinator Matt Canada, who replaced Randy Fichtner. The Steelers retooled their offensive line, and sought to upgrade the NFL worst-ranked running attack by drafting Alabama’s Najee Harris in the first round.

In Buffalo, the NFL’s second-best scoring offense returns 10 starters with the exception of veteran receiver — and former Steeler — Emmanuel Sanders brought in to replace John Brown.

Beasley spoke to how the continuity on offense instills confidence.

“We come out there with the mentality that nobody’s going to stop us, and we’re going to score,” Beasley said.

“I think that confidence built some last year, and even the year before that, but more so this year,” he added. We don’t hope it’ll happen. We expect it to. But it’s easier said than done.”