PITTSBURGH — Of all the improbable scenarios the Pittsburgh Steelers could have concocted during perhaps the most miserable offseason in the franchise’s history, this would be near the top of the list.

Dennis Dixon will be their season-opening quarterback today against the Atlanta Falcons.

Not Ben Roethlisberger, who is throwing passes to nondescript receivers at a high school stadium while he serves a four-game suspension for his off-field misbehavior. Not Byron Leftwich, who was reacquired to start while Roethlisberger was out but is sidelined with a left knee injury. Not Charlie Batch, who has been with the Steelers since 2002 and knows the playbook better than the coaches do.

Nope, it’s Dixon — a former fifth-round pick who was passed over multiple times by every NFL team in the 2008 draft.
Not since No. 1 pick Terry Bradshaw was the rawest of rookies in 1970, the Hall of Famer’s first and worst season, have the Steelers started so inexperienced a quarterback in their opener. Dixon has thrown all of 27 passes, started all of one game. His running skills might be the best of any NFL quarterback, yet his own offensive coordinator, Bruce Arians, said he won’t last a game if he tries to run too much.

Which raises some intriguing questions, not only for the Steelers themselves but also the Falcons.

Is starting a quarterback so unproven a decided disadvantage for the Steelers? Or does Dixon, with his ability to take off with the football at any moment, offer such a change from what the Steelers do with Roethlisberger that starting him might prove to be a strategical masterstroke by coach Mike Tomlin?

“He’s a dual threat,” wide receiver Mike Wallace said. “He can throw it, but at any time he can break those 40- or 50-yard runs. I expect him to control our offense and lead our team to a victory.”

Ask the Falcons, and they’ll take playing Pittsburgh without Roethlisberger any time.

“I mean, yeah!” tight end Tony Gonzalez said. “I’m just answering honestly. He’s a Pro Bowl player, he’s one of the best quarterbacks in the league — it will be like if we didn’t have Matt Ryan. ... At the same time, they’ve known that and prepared for that. The guy going in has a whole different skills set, a whole different dynamic.”

Safety Thomas DeCloud feels similarly, saying, “Not going against a team’s No. 1 quarterback is always somewhat of a leg up for the defense.”

The Steelers have started unproven quarterbacks before. Cliff Stoudt had thrown only 98 passes before replacing the injured Bradshaw in 1983. Kordell Stewart had thrown all of 37 passes, some in his so-called Slash role, before starting in 1997. But Dixon is even less experienced than they were.

“It’s so surreal,” Dixon said. “You envision this as little kid, starting in the National Football League, and to open up the season, too.”

A season that could offer considerable intrigue for both teams, whose last game at Heinz Field eight years ago resulted in a 34-all tie — one of only two NFL ties since 1997.

The Falcons, coming off consecutive 9-7 records that represented the first back-to-back winning seasons in franchise history, upgraded a pass defense that was the NFL’s fourth worst last season by signing former Texans cornerback Dunta Robinson. He missed all the preseason with a sore hamstring, but coach Mike Smith doesn’t expect him to be slowed today as he lines up against Hines Ward.

The Falcons’ offense badly missed former All-Pro running back Michael Turner as he sat out about half of last season with a high ankle sprain, which led to a drop in his rushing yardage from 1,699 in 2008 to 871. A healthy Turner would most benefit Ryan, who has thrown for 6,356 yards in two seasons.

“He’s a great running back,” Steelers defensive end Aaron Smith said. “If I was their coach, I’d give us a healthy dose of him.”

Ryan must try to decipher a 3-4 Steelers defense coached by Hall of Famer Dick LeBeau that welcomes back safety Troy Polamalu and defensive end Smith following injuries that kept them out much of last season. Without them, the Steelers dropped from No. 1 in overall defense during their Super Bowl-winning season in 2008 to No. 5, and they missed the playoffs with a 9-7 record.

“It wasn’t like we were horrible last year but, obviously, that’s behind us,” said Polamalu, a game-changing player.

The Falcons also will be dealing with a key suspension as defensive tackle Jonathan Babineaux sits out after being arrested last year on marijuana charges. Atlanta had only 28 sacks last season, and losing its top lineman against a team that is vulnerable to the pass rush won’t help. The Steelers allowed 50 sacks a year ago, and they’ll be without right tackle Willie Colon (torn Achilles) for the season.

They’re also missing former Super Bowl MVP receiver Santonio Holmes, who was dealt to the Jets following a series of off-field missteps.

The Steelers offered some hints what life without Roethlisberger will be like when they ran the ball on 72.5 percent of their preseason plays, easily the highest percentage in the league.

Rashard Mendenhall had a pair of 150 yards-plus games last season and figures to get all the carries he wants as the Steelers ease Dixon in.

The Steelers leaning on the running game and their defense? Sounds like old times.

“We want to be good all year, no matter who’s playing quarterback,” said outside linebacker LaMarr Woodley, who had 131/2 sacks last season.

“We want to be at our best from start to finish, and we’d better be that way if we want to make the playoffs.”