On Monday, Tomlin named Dennis Dixon the starter in Roethlisberger's absence.
When asked if Roethlisberger would regain his starting job upon his return, Tomlin told Sirius NFL Radio: "I'm going to dodge that one and not artfully.
"I'm not going to back myself in a corner."
Byron Leftwich, reacquired by Pittsburgh during an April trade, was expected to start while Roethlisberger was out, but sprained his left medial collateral ligament Thursday against Carolina. Dixon, a third-year player from Oregon, threw for a touchdown and ran for another during an overtime loss in Baltimore last season when Roethlisberger was out with a concussion.
"Dennis has had a very productive preseason and training camp," Tomlin said. "He went into the training camp as a young guy, second in the pecking order behind Byron Leftwich. He did a nice job and made it extremely competitive. He waged a battle and got some first-team reps in some preseason games. Largely, we've been very impressed with how he's handled himself in game situations."
Roethlisberger was not chosen as a Steelers captain in a vote by his teammates announced Monday. He has been selected the previous two seasons. Wide receiver Hines Ward and tight end Heath Miller will be the offensive captains
The Steelers knew for months Roethlisberger would be absent when the season began, but the reality of his punishment struck them as they reported for practice this week and found his No. 7 locker vacant.
"We've been anticipating this moment for some time, planning and so forth," Tomlin said Tuesday. "There's not any last-minute adjustment. It's just more about dealing with it."
What they're dealing with is an awkward, unenviable situation that could force the Steelers to adopt a late-season, win-or-else mentality in September.
The months of turmoil Roethlisberger created with his indiscretions ultimately may be viewed in the context of what the Steelers do during their month of uncertainty without him. Should they thrive with the playmaking Dixon at quarterback and get off to a fast start, the impact of Roethlisberger's missteps may be relatively minimal.
However, if the Steelers flop with their No. 3 quarterback in charge, Roethlisberger might be remembered as the man who brought down a season before it started.
"It's very tough, kind of emotional," Roethlisberger said before leaving the team. "I've just got to go do what I've got to do."
The bigger question is what the Steelers will do without him.
Dixon, picked by Tomlin over the more experienced Charlie Batch to start Sunday against Atlanta, is fast, athletic and an exceptional runner. But the former Oregon star has started only one NFL game, and a championship-contending team almost never goes so far down its depth chart at quarterback to begin a season.
Mostly because of their quarterback quandary, the Steelers -- winners of 24 games the last two seasons -- find themselves as home underdogs against Atlanta.
"That's good," Ward said. "We're going to be underdogs all year, especially the first four games, with the uncertainty of who we have at quarterback. We play better as underdogs."
He might be right. The 2005 Steelers, 7-5 with a month left in the season, knew they couldn't lose again if they were to win the Super Bowl, and they won eight in a row. The 2008 Steelers thrived while being challenged by perhaps the most demanding schedule ever played by a Super Bowl winner, going 12-4 before winning two playoff games and the Super Bowl.
Partly to recreate the dynamics of those seasons, the Steelers scrapped their unwritten policy of not bringing back former players to reacquire Leftwich, linebacker Larry Foote, cornerback Bryant McFadden and wide receiver Antwaan Randle El. The idea was to take one or two final runs at the Super Bowl with a still-talented but aging defense.
Now, this reunited group must try to keep the Steelers afloat until Roethlisberger gets back.
"That's one thing about this team," said defensive end Aaron Smith, who returns after missing most of last season with a shoulder injury. "We love performing for each other and being there for each other."
To Smith, that means a defense that was the NFL's best two seasons ago must carry the Steelers through this Ben-less stretch against Atlanta, Tennessee, Tampa Bay and Baltimore.
The last time the Steelers faced a comparable challenge without a franchise-type quarterback was in 1976, when Terry Bradshaw was injured for much of the season and rookie Mike Kruczek filled in by going 6-0 as a starter despite not throwing a single touchdown pass. That team had a defense loaded with Hall of Famers (Jack Ham, Jack Lambert, Joe Greene, Mel Blount) and another at running back (Franco Harris) to lean on.
This defense isn't as accomplished, yet it figures to be much improved with Smith and safety Troy Polamalu back. The Steelers lost five times while leading in the fourth quarter last season, largely because of their inability to defend against the deep pass. A healthy Polamalu could help fix that.
Running back Rashard Mendenhall ran for 1,108 yards in his first season as a starter a year ago and could take a lot of the pressure off Dixon if he gets going early.
Also unsettled is the question of how Roethlisberger will be viewed by the Steelers' large and passionate fan base once he returns Oct. 17 against Cleveland.
The accusation that he sexually assaulted a Georgia college student -- he was not charged -- led to his suspension and enraged countless Steelers fans in March and April. By August, Roethlisberger was greeted enthusiastically by fans during training camp, and his two exhibition home appearances attracted not one word of discernible protest.
Of course, the Steelers still haven't played a game that counts. Should they go 1-3 without Roethlisberger and then fail to recover once he returns, the fan reaction might not be nearly as cordial.
"If we don't win, there will be a lot of negative energy that will come out of this year," said Steelers fan Jeff Simpson, 34, of Clarion, Pa. "If they can pull off even a 10-6 season, make the playoffs, I think it will all be put in the past. And we'll all move on from there."
Information from The Associated Press was used in this report.