As defense struggles, Shanahan confident in coordinator Saleh

First, the 49ers’ defense had tackling issues this season.

Then the scrutiny turned to communications gaffes in the secondary.

Finally, in last Sunday’s 43-16 loss at Seattle, there were breakdowns in run defense.

Defensive tackle DeForest Buckner said the lack of attention to detail began in the previous week’s 27-9 loss at Tampa Bay. The 49ers allowed a seasonhigh 168 rushing yards to the Seahawks.

“Guys just have to own their jobs,” Buckner said. “Pay more attention and study a little more, including me. This goes for everybody.”

The 49ers enter Sunday’s meeting against the Broncos at Levi’s Stadium ranked 29th in points allowed (28 per game) and are on pace to shatter the NFL record for the fewest takeaways in a season. They do rank 12th in yards allowed (348.8), but their issues this season have prompted questions about the job security of coordinator Robert Saleh, 39, who never had a title higher than position coach before he was hired by head coach Kyle Shanahan last year. When asked whether Saleh will return in 2019, Shanahan has been unwavering.

“Saleh is a very, very good coach,” Shanahan said. “He always has been. He still is. And Levi’s Stadium

810, 107.7

WR Dante Pettis. So this is why the 49ers traded up 15 spots to select Pettis with the No. 44 pick in this year’s draft. After a slow and injury-plagued start, the rookie has shown others what the 49ers saw in him. In his past two games, Pettis has nine catches for 206 yards and three TDs. And his hot streak could continue Sunday: He’ll face a banged-up Denver secondary, and fleet WR Marquise Goodwin will return from a two-week absence, which could draw coverage from Pettis.

49ers — WR Pierre Garcon (knee), RB Matt Breida (ankle) and S Jaquiski Tartt (shoulder) are out. Broncos — CBs Chris Harris (fibula) and Tramaine Brock (ribs) are out.

THREE THINGS TO WATCH FOR

Saleh has dealt with attrition. The 49ers have started seven safety combinations and four Will linebackers, including Reuben Foster, a 2017 firstround pick who was released last month following his third arrest in 10 months.

Saleh almost surely will get another chance in 2019. However, in the midst of a 2-10 season, Shanahan didn’t rule out changes to his coaching staff.

“I know we’re going to have some tough decisions to make. Just personnel-wise, possibly staff-wise. Just the whole building,” Shanahan said. “… When you do have a bad year like we have, just record-wise, I know that’s what people want: They want drastic change (and) they want quick answers.

“The key, though, is to get it

Year-by-year win totals for the 49ers and Raiders (in the Super Bowl era):

Wins

he’s not a finished product either — like we all aren’t. I think Saleh will continue to get better because he works at it. He’s very smart and I think he’s good right now.”

The 49ers’ inability to harass quarterbacks into mistakes is a huge reason they have an NFLlow five takeaways and could break the record for fewest in a season (11). Since 2017, the 49ers rank 25th in the NFL in sacks (59) and 32nd in takeaways (25).

And the front office has to assume some blame for that.

The 49ers have selected one true edge rusher — 2017 sixthround pick Pita Taumoepenu — in the past two drafts. Outside the draft, their biggest move to address the position has been to sign Cassius Marsh — their primary edge rusher this season — to a contract extension after claiming him off waivers in 2017.

The 49ers did use last year’s No. 3 pick on defensive lineman Solomon Thomas, and they envisioned him providing outside pass-rush pressure. However, Thomas has four career sacks in 26 career games. On Friday, Lynch’s comments about Thomas made it clear the 49ers overestimated his versatility.

“What I’ve been excited about — and it took some time — I think he’s being played where he’s going to thrive in this league: It’s more inside,” Lynch said on KNBR.

As far as other positions,

Super Bowl championship seasons Broncos (6-6) at 49ers (2-10) Where: When:

TV: Radio:

Spotlight on:

Injury report:

1:05 p.m. 鉔 George Kittle (893 yards) needs 73 yards to break Vernon Davis’ franchise season record for receiving yards by a tight end. Denver is allowing 63.9 yards per game to tight ends, seventh most in the NFL.鉔 The Broncos had a season-high 218 rushing yards, 157 from undrafted rookie Phillip Lindsay, in last Sunday’s 24-10 win over the Bengals. The 49ers allowed a season-high 168 rushing yards last Sunday in a 43-16 loss at Seattle.

鉔 The Broncos are tied for seventh in the NFL in turnover margin (plus-8). The 49ers rank 32nd (minus-20).

WORST POINT DIFFERENTIALS

Years the Bay Area teams were outscored by the most combined points:

Year right and to make sure you do the best thing possible to put our team in the best (position) to win. That’s what we’re going to do hard after this year.”

Shanahan fined: In a rare move, the NFL fined a head coach for arguing with officials, docking Shanahan $25,000 for unsportsmanlike conduct last Sunday against Seattle. Shanahan was flagged for arguing after Seahawks quarterback Russell Wilson tossed the lost shoe of linebacker Fred Warner to the side after a play. Seattle then went hurry-up offensively and the 49ers were offsides.

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch

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2006 2007 2014

Differential

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