Even after the high-profile retirements of Hines Ward, Aaron Smith and Chris Hoke and the apparent retirement of James Farrior, the Steelers remain a largely veteran group. Seven projected defensive starters are in their 30s. Nine of those 11 have been starters for the Steelers for multiple seasons, and 10 have started last season.

There's more youth on offense, where only quarterback Ben Roethlisberger is 30. But outside of two high-profile position battles on the offensive line, many of the "starters" are set. That doesn't mean there aren't some impact roster spots and roles up for grabs with the preseason set to get underway Thursday at Philadelphia.

Questions to be answered in exhibition season:

1. Can rookies David DeCastro and Mike Adams not only win starting jobs on the offensive line but excel at their positions? Pittsburgh's first- and second-round picks, DeCastro and Adams, are in the starting lineup for their preseason debuts. That's heady stuff, although it should be noted that injuries are playing a part in each getting that opportunity. Willie Colon's absence opened up a guard spot for DeCastro and Max Starks' continued rehab from a torn ACL has allowed Adams to run with the first team. Still, each has the pedigree, big-time college experience, size and skill to potentially start regular-season games in the NFL right away. Adams quickly bypassed journeyman Trai Essex on the depth chart at left tackle, but DeCastro hasn't definitively shaken Ramon Foster at right guard (Foster moves over to left guard with Colon out). The starters for both teams figure to only get a series or two, although coach Mike Tomlin indicated Adams and DeCastro could get extra reps. It will be interesting to see how Adams fares against a live pass rush and if DeCastro looks better in game action -- with the pulls and quick decisions -- than he has on the practice field.

2. With Mike Wallace nowhere to be seen, there's a receiver's job to be had. Who's going to step up and take it? With Wallace's holdout into its third week, the Steelers are preparing for life without their speedster. Not having their No. 1 receiver would hurt the offense, no doubt. But the bigger problem for the Steelers might not be the No. 1 receiver spot as much as No. 4 or No. 5. With Wallace nowhere to be found at St. Vincent College, the domino effect has made the Steelers weaker down the line at the position. Emmanuel Sanders has the potential to be a very good slot option, but as the downfield "X" receiver? Jerricho Cotchery as a crafty veteran No. 4? You're in business. As you're No. 3 -- in today's game, that often means you're on the field for more snaps than you're not -- he's not as imposing. Then, of course, is the issue of who is No. 4. Someone among the group of Derrick Williams, David Gilreath, Marquis Maze, Tyler Beiler, Jimmy Young, Toney Clemons, Juamorris Stewart or Paul Cox will be. Of that group, only Williams has an NFL reception (he has nine over two seasons and none since 2010). Bottom line: Hope Sanders' balky feet are 100 percent healed and that neither he nor Antonio Brown or Cotchery get injured. Or simply hope that Wallace shows up.

3. Can Keenan Lewis hold off Cortez Allen at left cornerback? The only position battle involving veteran combatants is opposite Ike Taylor in the secondary. Lewis has been serviceable since being drafted in the third round in 2009, climbing his way up the depth chart to the point he was a reliable nickel back last season. When William Gay signed with Arizona as a free agent, Lewis was slotted as the placeholder in the lineup. But Allen, a fourth-round pick last year, has exceeded the Steelers' expectations with the way he has adapted to the NFL game after not picking up football until his senior year of high school and playing college ball at The Citadel. He was viewed more as a longterm project at this point last year but by the end of the season had already worked his way into the playing-time rotation. Lewis has been limited by a shoulder injury during camp (his status for the Eagles game is up in the air), opening up even more of an opportunity for Allen. Should Allen win the job, it would give the Steelers two starting cornerbacks with startling similar resumes. Both Taylor (6-2, 195) and Allen (6-1, 196) are big, went to smallish-schools (Taylor played at Louisiana-Lafayette), were taken in the fourth round by the Steelers (Taylor in 2003) as the second cornerback the team chose in that given year. Taylor contributed right away, was a starter by his third season and has been a reliable starter on three teams that made the Super Bowl since. Entering his second season, Allen might be ahead of that pace.

Follow Steelers reporter Chris Adamski on Twitter @CBSSportsNFLPIT and @BuzzsawPGH.