SANTA CLARA -- The 49ers haven’t done much in free agency. In fact, they haven't added a single player to a defense that finished 29th overall last season. When they assemble for the start of the offseason program next week, the roster will be nearly identical to how it looked at the end of last season, at least from a personnel perspective. The only difference -- albeit a big one -- is the coaching staff. Here’s a stab at a rough depth chart for the beginning of the offseason.
Defensive end: Quinton Dial, Arik Armstead, Glenn Dorsey, Kaleb Ramsey
Notes: Armstead improved over the course of his rookie season and the 49ers will look for him to expand -- perhaps drastically -- on his 375 snaps from last season. Ramsey never has taken a regular-season snap. Dorsey tore his ACL Nov. 22 and his Week 1 availability is in doubt. Backup Tony Jerod-Eddie, a free agent, has a modest contract offer on the table but has not signed it.
Nose tackle: Ian Williams, Mike Purcell, Garrison Smith
Notes: Williams' availability for Week 1 is fuzzy after offseason ankle surgery. Purcell made a splash in the 2015 preseason, then built on it with 288 defensive snaps toward the end of the season, most of them at defensive end. Smith has yet to make his NFL debut.
Outside linebacker: Aaron Lynch, Ahmad Brooks, Eli Harold, Corey Lemonier, Tank Carradine, Marcus Rush.
Notes: Lynch may be the best young player on defense. But he battled back issues last offseason and finished with 6 1/2 sacks, which tied for 39th best in the league. Harold, a third-round pick last year, didn't have any sacks. But he improved as the season went on and the 49ers are hoping that some added bulk will translate to more explosive plays in his second year. Carradine probably will be listed as a defensive lineman. But at 265 or so pounds, he'll be the same size as the team's outside linebackers and will be used in the same situations -- rushing from the edge when the 49ers are in their nickel defense.
Inside linebacker: NaVorro Bowman, Michael Wilhoite, Gerald Hodges, Shayne Skov, Ray-Ray Armstrong, Nick Bellore
Notes: That Bowman started all 16 games in 2015 was a monumental accomplishment following a year away from the game. He should be even better in 2016. Wilhoite, Hodges and perhaps a draft pick will compete to play next to Bowman this season. Bellore is a kick-coverage specialist brought in by the 49ers' former special teams coordinator. The new one, Derrius Swinton, has yet to bring in any former players, a good sign for Bellore.
Cornerback: Tramaine Brock, Dontae Johnson, Jimmie Ward, Marcus Cromartie, Kenneth Acker, Keith Reaser, Chris Davis
Notes: The 49ers never settled on a starter opposite Brock in 2015, and that battle will begin anew with the incoming coaching staff. Johnson and Cromartie have the size the 49ers have preferred in the past at the position. At one point, team officials thought Reaser would rise to the top of the position. Instead he played scant snaps last season. Ward quietly had a strong season as the team's nickel cornerback.
Safety: Eric Reid, Antoine Bethea, Jaquiski Tartt, L.J. McCray
Notes: This is the team's strongest position and one of few spots where the 49ers don't need draft help. In addition to the names above, Ward could play either safety spot if there are injuries.