Lineups aren't set in every case. Injuries are affecting a few situations. We're still able to put together a snapshot visible in the chart at the bottom of this entry.
Among the considerations:
Arizona Cardinals: I've got Antoine Cason as one starting cornerback. Daryl Washington remains a projected starting linebacker despite his four-game suspension. Karlos Dansby is also in the lineup, leaving out 22-year-old rookie Kevin Minter, who obviously figures into the team's plans.
Seattle Seahawks: Cliff Avril, 27, is penciled in as a starting defensive end while Chris Clemons, 31, recovers from knee surgery. The Seahawks are experimenting with quite a few combinations on defense, so there could be changes. I moved rookie Jesse Williams into the lineup at defensive tackle over veteran Tony McDaniel, 27.
San Francisco 49ers: The totals for the 49ers stay the same in each category if Mario Manningham subs for Michael Crabtree at receiver. The 49ers would gain a starter under 25 years old if A.J. Jenkins ascended to the role. I've projected rookie Eric Reid, 21, as one starter at safety.
St. Louis Rams: Left guard candidates Shelley Smith and Chris Williams are both in the 25-29 range, but the chart would change if you moved Rokevious Watkins, 24, into the lineup at their expense. I've got Alec Ogletree starting at linebacker. He is 21.
Reid and Ogletree are the youngest projected starters in the division, followed by 22-year-olds Tavon Austin, T.J. McDonald, Michael Brockers, Williams and Bobby Wagner. Wagner, who started as a rookie for Seattle last season, turns 23 later this month.
Seattle's Earl Thomas and San Francisco's Anthony Davis are among three players from 2010 through last season to have started all 48 regular-season games before turning 24. The New York Giants' Jason Pierre-Paul is the other.