LATROBE, Pa. -- The Steelers just completed their 47th training camp at St. Vincent College. Before they arrived, the team reached a contract extension with Mike Tomlin, who is the Steelers' third coach over the past 43 years.

In other words, this organization believes in stability and continuity. That's why changing offensive systems -- switching from Bruce Arians to Todd Haley at coordinator -- has been a different challenge heading into the 2012 season. If the Steelers want to grab hold of their seventh Lombardi Trophy, the players know they have to gain a firm grasp on the new playbook.

No one is saying what Haley's offense will look like. And honestly, you get the feeling that the players really don't know the identity of the Steelers' offense yet.

"I don't, but Todd might," quarterback Ben Roethlisberger said without a hint of trying to be coy. "Because a big part is the injuries. We don't know what's going on with all the injuries. So, we don't know yet. Whatever we decide to do, we just want to be the best at what we can be at that."

Training camp has been a series of constant adjustments for the offense. Mike Wallace, the Steelers' top wide receiver, remains a holdout because he wants a long-term contract. During my two days at camp, Isaac Redman, the projected starting running back, couldn't last one full practice because of a groin injury. On the offensive line, only two starters (center Maurkice Pouncey and right guard David DeCastro) are at the same spots they started in the preseason opener.

When the Steelers get healthy, some expect the offense to be a run-heavy attack like the one Haley ran with the Chiefs. Steelers president Art Rooney II said he wants the Steelers to run the ball more consistently this season.

Others see the Steelers relying on Roethlisberger's arm and the playmaking ability of Wallace and receiver Antonio Brown. Haley directed one of the NFL's top passing attacks a few years ago when he was the coordinator with the Cardinals.

Haley's vision for the Steelers appears to be somewhere in the middle of what he did in Kansas City and Arizona.

"I would think that one of our strengths is versatility," Haley said. "You don’t want to do a lot of things just OK. You’d like to do some things real good. I think with some of the ability we have, and if our line continues to jell together and gets better every week, we have a chance to be a pretty versatile group that can hurt you in a number of ways."

Learning a new offense is still a work in progress for the Steelers, although it's not as bad as May, when Roethlisberger referred to Haley's playbook as Rosetta Stone.

After drills, it's not uncommon to see Roethlisberger huddle with his top three receivers (Brown, Emmanuel Sanders and Jerricho Cotchery) to go over what happened. Roethlisberger also stays after practice to work on routes with his receivers.

"I feel like I got a pretty good grasp," Roethlisberger said of the offense. "If the regular season started tomorrow, I would be a little disappointed because I would want to be even more comfortable. The good thing is I have three more weeks to get to that point where I feel extremely comfortable."

Roethlisberger added, "Now I'm not going to be as comfortable in this offense, even probably in Week 15, as I would be if it was the same offense I've been [in] for nine years. That's common sense. But I feel like every week and every day, you feel more comfortable in this system and what Todd wants."

THREE HOT ISSUES

1. Mike Wallace's absence. To protest the fact that he doesn't have a long-term contract, Wallace didn't report to training camp, which officially made his holdout the longest by a Steelers player in 22 years. The Steelers suspended talks on a new contract until Wallace returns to the team and signs his $2.7 million restricted free-agent tender. This stalemate is expected to end over the next couple of weeks, so Wallace can be ready to play in the Sept. 9 regular-season opener. That would also allow the sides some time to reach a deal before the season, which could (but probably won't) happen.

While Wallace isn't the most popular person in Pittsburgh for skipping camp, he remains the top offensive player on the Steelers, outside of Roethlisberger. Only two receivers in the past 30 years have gained more receiving yards and scored more touchdowns during their first three years than Wallace: Jerry Rice and Randy Moss.

So how long will it take for Wallace to get ready to play after reporting?

"I think it depends on a lot of things," Roethlisberger said. "I think if they bring him in and he's playing one position and he's been looking at what coach has sent him, I think he'll be able to pick it up and be ready to go. He may not be as ready in Week 1 as the rest of the receivers are. But I will spend some extra time with him if he wants out on the field, throwing and doing whatever we have to do to make sure he's caught up to speed."

2. Who's the No. 2 cornerback? Barring some major developments over the next three preseason games, this spot is expected to go to Keenan Lewis, who's been having a strong camp. He's impressed coaches by paying attention to detail and not having busted assignments. Lewis tightened his grip on the starting job when he hurt his shoulder early in camp and put in a full practice two days later. Toughness always catches the eyes of the Steelers.

Cortez Allen, Lewis' chief competition, has also showed improvement. He's been able to use his athletic ability more this year because he has a better understanding of the defense. Even though he probably won't unseat Lewis as a starter, Allen will get on the field as the team's nickelback. Curtis Brown has faded from this competition after giving up two touchdowns in the preseason opener.

With Ike Taylor starting at the one cornerback spot, the Steelers expect quarterbacks to go after Lewis and Allen. "They'll get tested every week," secondary coach Carnell Lake said. "But if you enjoy playing this game and especially enjoy your job at corner, that comes with it. Actually, you want the challenge because that's what you do."

3. Injuries at running back. The Steelers' top three running backs -- Rashard Mendenhall, Redman and Jonathan Dwyer -- have all missed time in camp because of injuries. There have been times when Pittsburgh has been down to two healthy running backs, Baron Batch and Chris Rainey. It makes you think the Steelers should hold their running back meetings in the trainer's room.

Mendenhall, the team's leading rusher for the past three seasons, was just removed from the physically unable to perform (PUP) list after having ACL surgery in January. Redman is expected to miss Sunday night's preseason game because of a groin injury. And Dwyer came back to practice late last week after being sidelined with a a shoulder injury.

With Mendenhall not expected to play in September, the plan is to go with Redman to start the regular season. An undrafted rookie out of Bowie State in 2009, Redman gained 121 yards in the Steelers' playoff game in Denver. "He’s a big, downhill back that’s excellent in protection," Haley said. "As a runner, you can’t pigeonhole him and say he’s strictly a between-the-tackles runner, because I do think he has a little sneaky burst to the edge."

REASON FOR OPTIMISM

The Steelers are once again among the Super Bowl favorites, and it goes beyond defensive end Brett Keisel's prediction of sorts. It seems that every time Keisel welcomes a new child, the Steelers go to the Super Bowl. The Keisels welcomed their third child last week. "So, I want that trend to continue," Keisel said.

All joking aside, Pittsburgh is a strong contender this year because its quarterback is entering the prime of his career and its top-ranked defense returns all but two starters. At running back, Redman may end up being a better runner than Mendenhall, who seemed hesitant running between the tackles. And few defenses can match up against Wallace, Brown and Sanders at wide receiver.

"This is probably the most talent I've seen on this team in years," said Taylor, who has been on two of the Steelers' Super Bowl-winning teams.

REASON FOR PESSIMISM

The Steelers invested their top two picks in the draft (guard David DeCastro and tackle Mike Adams) in their offensive line, and this group should be one of the best in a few years. But the concern is that the growing pains on the line could lead to more pain for Roethlisberger, who has endured more sacks and injuries than any other quarterback in recent years. An offensive line that went through a league-high 25 different combinations in the 2011 regular season is already on its second heading into the second preseason game. The Steelers have proved they can win some regular-season games without Roethlisberger, but they won't go far in the postseason unless he's healthy.

While the Steelers have the talent to be a top-10 offense, they need Roethlisberger and Haley to have a solid working relationship to do so. Haley is known for being an in-your-face coach, and Roethlisberger has made it clear that he doesn't need a coach to yell at him. Both also have strong philosophies for offensive success. This is a new situation for Roethlisberger, who was very close with his former coordinator, Bruce Arians. No one truly knows whether the Roethlisberger-Haley pairing will work until the pressure of the regular season arrives.

On defense, the Steelers need to generate more of a pass rush than last year, when they ranked 17th with 35 sacks. Pittsburgh can't allow quarterbacks to have time to target Lewis and Allen in the secondary, which is the weak spot of the defense. The Steelers need a healthy James Harrison and LaMarr Woodley to produce a more consistent pass rush. Harrison is considered questionable for the season opener after having his knee scoped.

OBSERVATION DECK

• The biggest beneficiary of Wallace's holdout has been Antonio Brown. Not only did Brown get a long-term deal, but he has developed better chemistry with Roethlisberger in Wallace's absence. Roethlisberger spends time after practice throwing to Brown, and the extra work has paid off. During one red zone drill, both of Roethlisberger's touchdown passes went to Brown.

• Pouncey is moving around great, which is a sign that his ankle problems have been resolved. He's also in the best condition of his three-year NFL career. "I keep joking with him, saying he's lost some of his baby fat because he's so young," Roethlisberger said. "He came back in great shape."

• There has been no drop off in going from Casey Hampton to Steve McLendon at nose tackle. McLendon has showed his strength by holding his own in the camp matchup with Pouncey. There's no need to rush back Hampton, who just came off the PUP list after knee surgery in January. Alameda Ta'amu, a rookie fourth-round pick, was originally tabbed as Hampton's eventual replacement, but he has looked like a rookie so far.

• Tight end Heath Miller was expected to be featured more in Haley's offense, but that remains to be seen after what happened in camp. Miller didn't get many passes thrown his way, and he wasn't even on the field on a third down in a red zone drill.

• One of the challenges of camp is trying to locate Rainey, who moves all around from running back to slot receiver to returner. Because the rookie is being asked to play so many different roles, it's going to take him time to master them. Rainey has shown flashes of being a dangerous playmaker. "He’s still got a long way to go," Haley said. "We’re not going to start carving the bust yet for Rainey."

• Lewis, who is expected to win the No. 2 cornerback job, is making fewer mistakes in this camp than previous ones. But during my two-day visit, Lewis always played 6 or 7 yards off the line. One reason for that is he's playing with a separated shoulder. But there will be times when he has to physically match up against the likes of A.J. Green, Anquan Boldin and Greg Little.

• Fullback Will Johnson is more than just a good story. Out of football last year, Johnson is showing he can run with the ball in addition to being a lead blocker. The Steelers need him to step up after David Johnson went down with a season-ending injury in the preseason opener.

• Dwyer has slimmed down, and it shows in his burst. Tomlin twice commented on Dwyer's cutting ability during one practice. His improved play could force the Steelers to give him more carries than previously expected this season.

• Byron Leftwich has done nothing to change the Steelers' mind about giving him the No. 2 quarterback job. It still amazes me that Leftwich has not changed his throwing motion since being drafted in 2003. His windup delivery is slow and awkward.