Defense faces daunting task
Eliminating mistakes will be focus against high-scoring Arizona
SANTA CLARA — Missed tackles, blown assignments and big-play generosity have become the uncharacteristic hallmarks of the 49ers defense.
Now the 49ers are preparing to face the NFL’s top-ranked offense, as the Arizona Cardinals visit Levi’s Stadium on Sunday.
“As they say, the show must go on,” safety Eric Reid said Wednesday, in the wake of allowing 209 rushing yards to undrafted rookie Thomas Rawls in a 29-13 loss at Seattle.
“Unfortunately, injuries happened, and we miss some guys that left,” Reid added. “You keep fighting and hold guys accountable next to you.”
Getting to know the guy next to you is an increasing chore for a defense that used to be known as a perennial power.
Defensive tackle Glenn Dorsey (knee) has joined strong safety Antoine Bethea (pectoral) on season-ending injured reserve, robbing the 49ers of two veterans known as much for their leadership as their steady play.
Of course, the defense already has had trouble adapting without mainstay players from past years: Justin Smith, Patrick Willis, Aldon Smith, Ray McDonald, Chris Culliver, Perrish Cox, Chris Borland and more.
The 49ers defense ranks 28th overall in yards allowed per game and 27th against both the pass and rush.
Coach Jim Tomsula said the 49ers must cut down on mental mistakes and presnap penalties. “It’s hard enough defeating the opponent,” Tomsula said this week. “Don’t do things that make you have to compete against yourself.”
Playing error-free defense has been an incomplete task.
“It seems like every week it’s something else,” Reid said. “We fix something from one week, then falter elsewhere. We’ve got to fire on all cylinders, and this is the best game to do that.”
Dorsey is the latest to exit, going down on the first snap Sunday, and his impact became apparent with every yard Rawls gained.
The 49ers (3-7) will take a different tack at replacing Dorsey against Arizona (8-2), which leads the NFL with 33.6 points per game.
Defensive tackle Quinton Dial is expecting to shift from the left side to the right, where Dorsey had started every game this year. First-round draft pick Arik Armstead will get plugged in on the right side, and Tony Jerod-Eddie should see action there, too.
“What Glenn brought to the table was a lot of experience,” Dial said. “With Arik, he’s young and we’re trying to bring him along as fast as we can.”
Another factor could be Tank Carradine, who was inactive last Sunday. Carradine is switching from a defensive tackle role into more of a third-down, passrushing specialist, where he took all of last week’s scoutteam reps.
“He had a nice week of practice last week,” Tomsula said of Carradine’s role adjustment. “You don’t do this in five days. … He’s changed the way he’s training. You can already see he’s slimmed down in his hips and things.”
The 49ers pass rush practiced Wednesday and Thursday without Ahmad Brooks, as the outside linebacker was placed into the post-concussion protocol. Eli Harold or Corey Lemonier would be in line to start if Brooks’ condition doesn’t improve.
In the secondary, the 49ers are still mixing and matching, as coaches are creating time for reserves Marcus Cromartie and Dontae Johnson.
In the 49ers’ last meeting with Arizona, a 47-7 loss on Sept. 27, Carson Palmer passed for 311 yards and two touchdowns.
“Carson’s having a great year. Their receivers are having a great year,” Reid said. “They’re doing a lot right. We’ve got to make sure they don’t get behind us on defense because Carson loves to throw the deep ball.”
Quarterback McLeod Bethel-Thompson, signed Tuesday to the practice squad, is not being rushed into the No. 2 role occupied by rookie Dylan Thompson. Tomsula said it’s “not likely” that Bethel-Thompson will be promoted to the 45-man roster for Sunday.
The 49ers and the Baltimore Ravens had attempted to poach San Jose State product David Fales off the Chicago Bears’ practice squad, prompting the Bears to promote Fales to their 53-man roster Monday and release Jimmy Clausen, the Chicago Sun-Times reported.
The 49ers will wear their alternate, black uniforms Sunday for the second and final time this year. They won in them against the Minnesota Vikings in the season opener.
Quinton Patton’s playmaking ability on special teams — as a gunner in coverage and a leader in meetings — has gained respect from coordinator Thomas McGaughey. “Quinton is like the old Mosel tree,” McGaughey said. “He’s kind of spread his roots in the ground and now all of a sudden he’s going up vertically. It is beautiful to watch a kid like that really start to spread his wings and really start to mature.”
All fans will receive a scarf as part of the 49ers’ “Faithful Appreciation” game. For more on the 49ers, see Cam Inman’s Hot Read blog at blogs.mercurynews. com/49ers.