Our two-day look at NFC West rosters continues with projections for the San Francisco 49ers’ defense and special teams.

Defensive linemen (10)

Average number kept since 2003: 7.0

Safest bets: Justin Smith, Ray McDonald, Isaac Sopoaga, Ricky Jean Francois

Leading contenders: Will Tukuafu, Demarcus Dobbs, Ian Williams

Longer odds: Patrick Butrym, Matthew Masifilo, Tony Jerod-Eddie

Comment: The top three are firmly entrenched. All are playing at a high level. The 49ers might want to address this position in the 2013 draft. For now, though, they're set. San Francisco kept seven defensive linemen on its Week 1 roster last season. Tukuafu, Dobbs and Williams combined to play about five percent of the defensive snaps.

Linebackers (13)

Average number kept since 2003: 7.6

Safest bets: Patrick Willis, NaVorro Bowman, Aldon Smith, Ahmad Brooks, Parys Haralson, Larry Grant, Tavares Gooden

Leading contenders: Cam Johnson, Kourtnei Brown, Eric Bakhtiari

Longer odds: Michael Wilhoite, Joe Holland, Darius Fleming (injured)

Comment: The 49ers have kept eight linebackers on their Week 1 roster for each of the past six seasons. Brown, an undrafted rookie from Clemson, stands 6-foot-6, weighs 255 pounds and moves well. He's also raw and has had injury problems. Johnson, a seventh-round choice, might need to fight off Brown and the more experienced Bakhtiari for a roster spot. Special teams will be a determining factor.

Defensive backs (17)

Average number kept since 2003: 10.0

Safest bets: Carlos Rogers, Donte Whitner, Dashon Goldson, Tarell Brown, Chris Culliver, C.J. Spillman

Leading contenders: Perrish Cox, Trenton Robinson, Curtis Holcomb, Tramaine Brock, Colin Jones

Longer odds: Ben Hannula, Mark LeGree, Michael Thomas, Deante' Purvis, Cory Nelms, Anthony Mosley

Comment: The 49ers lack experienced depth at safety. They could go young this season or consider adding a veteran later. Robinson, a sixth-round rookie, took some first-team reps while Goldson stayed away as an unsigned franchise player. Spillman also worked with the starters. The undrafted Thomas could have the inside track for a practice-squad spot after playing for coach Jim Harbaugh and defensive coordinator Vic Fangio at Stanford. Holcomb, a seventh-rounder in 2011, is coming off Achilles surgery.

Special teams (5)

Average number kept since 2003: 2.9

Safest bets: Andy Lee, David Akers, Brian Jennings

Leading contenders: none

Longer odds: Giorgio Tavecchio, Kyle Nelson

Comment: All three specialists earned Pro Bowl honors last season.