Since Jim Harbaugh became head coach and installed defensive coordinator Vic Fangio, the 49ers defense has been one of the best and most consistent in the NFL.
But as the Niners get ready to face the Cowboys Sunday, that defense has been put the grinder. The unit that starts Game 1 of the regular season will be far different than the one that started the NFC Championship Game against Seattle in January.
Nose tackle Glenn Dorsey and inside linebacker NaVorro Bowman are out with injuries. Outside linebacker Aldon Smith is suspended. Cornerbacks Tarell Brown and Carlos Rogers, plus safety Donte Whitner, are playing elsewhere.
So six of Sunday’s 11 defensive starters will be new, and several who are in the lineup – inside linebacker Patrick Willis, nose tackle Ian Williams, safety Antoine Bethea and cornerback Chris Culliver – are either returning from a long time on injured reserve or recent injuries in training camp.
So the question is, how well can this unit be expected to play against a Dallas offense that can be explosive with quarterback Tony Romo and some athletic, deep-threat wide receivers?
Plus, this unit will face some of the NFL’s most dangerous quarterbacks in the first half of the season before Smith and Bowman are expected to return, including the Bears’ Jay Cutler Sept. 14, the Eagles’ Nick Foles on Sept. 28 and the Broncos’ Peyton Manning Oct. 19.
Fortunately, the 49ers have outstanding depth. Corey Lemonier, Dan Skuta and Aaron Lynch can fill in for Smith, Michael Wilhoite and Chris Borland will back up Bowman, Williams and Culliver have experience playing key roles from before their injuries and coaches believe Bethea will be a smart, capable leader in the revamped secondary. Also, second-year defensive linemen Tank Carradine and Quinton Dial had strong training camps and should help keep the defensive line fresh.
Fangio, in fact, said in August that he believes the defense will be OK because the 49ers have been able to prepare to plug the gaps. Most of the absences aren’t surprises.
“It’s more of an issue when it happens in the middle of the season, just thrown at you like it happened last year,” said Fangio of the changes, including the suspension of Smith for nine games. “Then there’s no time to adjust. You just go.”
Fangio has a history of successfully adapting to change. Last season, rookie safety Eric Reid stepped in as a starter and Dorsey took over for Williams in Game 2 without missing a beat. And Wilhoite, Lemonier and Skuta played big roles when Willis and Bowman missed playing time. Last season, too, Tramaine Brock emerged at cornerback and won a starting job.
So, while it’s obvious the 49ers defense has more question marks than at any time during the Harbaugh era, Fangio may be able to pull some new parts together to keep the machine humming.
As Matt Barrows of the Sacramento Bee noted, the 49ers have finished in the top five in total defense every season since 2011.
“If they even come close to No. 5 this season, it could be Fangio’s most masterful coaching performance yet,” he wrote.