49ers’ new-look defense gets its first test and Robert Saleh is looking forward to it

SANTA CLARA — Robert Saleh, the coordinator/savior of a maligned defensive unit, is eager to find out if what he’s seeing through 11 practices will translate against an opponent.

The 49ers host Denver for a joint practice session Thursday in advance of their preseason opener Saturday against the Broncos at Levi’s Stadium.

It’s been a complete rebuild of a defense that showed signs of trouble early last season before collapsing completely down the stretch, against both the run and pass. While the personnel makeover was dramatic, the fan base would have you believe the biggest move was when Kyle Shanahan removed Nick Sorensen as defensive coordinator and brought back Saleh, who ran the 49ers defense from 2017-20.

The difference is that while it took Saleh and the 49ers two seasons to get into gear before becoming dominant during his first stint, this time it needs to happen almost immediately.

Much has been made about the influx of rookies expected to play right away — defensive linemen Mykel Williams, Alfred Collins and C.J. West, and slot corner Upton Stout. Nick Martin is contending at linebacker. Marques Sigle could play at safety before the end of the season.

“I think of all the major sports, the NFL relies on rookies more than any of them,” Saleh said Tuesday. “You come in and it’s like throw your kid in the water and just go swim, right? They’re going to make mistakes. The hope is they’re smart enough or can acclimate well enough where they don’t make the same mistake twice.”

Throw in veteran acquisitions such as safeties Jason Pinnock and Richie Grant, linebacker Luke Gifford and cornerbacks Dallis Flowers, Trey Brown and Siran Neal, and it’s a lot of learning both in the meeting rooms and on the fly.

“It’s a real cool mixture of veterans along with a bunch of young guys that are injecting renewed youth into the vets,” Saleh said.

Saleh estimates there could be as many as eight new starters — although Nick Bosa, Fred Warner, Deommodore Lenoir and Renardo Green classify as incumbents and Dee Winters started 10 games last season.

“We knew what we were getting into,” Saleh said. “That’s the exciting part.”

With all the new faces, Saleh feels fortunate to be able to compete against the 49ers offense on a regular basis. Especially against the running game.

“They’ve got every run, I think, in the history of football,” Saleh said. “There’s different blocking combinations, trap blocks, wham blocks, outside zone, inside zone, duo double teams. If you’re not on it, you can just get washed out of the place. We get to see all the different blocking combinations and have a chance to work against them.”

The 49ers will have a walkthrough closed to the media Wednesday before getting a look at something new on Thursday against the Broncos.

“Sometimes you get into a routine where you’re recognizing the same bodies, same players, same stems, same formations,” Saleh said. “The challenge now is going to be a completely new opponent with no preparation because we’re not preparing for Denver. We’re just lining up — throwing it on the field and seeing how they play.”

THE MCKIVITZ REPORT

Right tackle Colton McKivitz had glowing reviews for the 49ers’ youthful new defensive line. He talked up Williams, Collins and West, as well as undrafted free agent Sebastian Valdez, who has been nicknamed “Little Hulk.”

“All these guys, they’re young and we’re going to ask them to do a lot,” McKivitz said. “Obviously they’re going to be a key to this team’s success. I think they’re going to make a lot of splash plays.”

STOUT’S HOLD ON SLOT CORNER

A day after Shanahan made it sound as if Stout had pretty much sealed the deal as the starting slot corner, Saleh was a little more measured in his assessment.

“You can say he’s got the inside track, but we’re in a marathon and we haven’t completed the first leg yet,” Saleh said.

MARTIN READY TO TURN IT LOOSE

Known as a fearless hitter at Oklahoma State, Martin concedes Shanahan’s insistence on not tackling to the ground and keeping people on their feet during practice takes some getting used to. He understands it, however, and is thrilled there will be no such limitations Saturday.

“I’m excited to live the dream for real and actually finish these plays,” Martin said.

PRACTICE HIGHLIGHTS

— Ricky Pearsall continues to excel. He has caught passes in traffic but even more impressive has been one of the few wide receivers to constantly separate and break into the clear.

— Linebacker Dee Winters, who looks to be in line to be in line for the Dre Greenlaw role as Fred Warner’s running mate in the nickel defense, stuck with Christian McCaffrey stride for stride and broke up a deep ball at the goal line.

“His coverage ability is as good as anybody,” Saleh said. “You trust him in those situations. Normally you don’t want to be in a call that puts a back one-on-one, but we gave him the op and he won.”

— Another good day for quarterback Brock Purdy, although he’d like to have back a pass over the middle that was intercepted by safety Richie Grant. Purdy has thrown less to Demarcus Robinson the last two days and appears to have complete trust in Pearsall and tight end George Kittle.

Purdy did have a couple of late connections with rookie fourth-round pick Jordan Watkins.

— Deommodore Lenoir (hip) was back to full-time duty after being limited Monday and had a nice pass breakup along the sideline while defending Kittle.

— While the 49ers have closely monitored the practice time of McCaffrey, Nick Bosa and Trent Williams, Kittle doesn’t appear to have missed a rep through 11 practices.

— With no one to kick against, place kicker Jake Moody got six field goal attempts from 33 yards back to past 50 and appeared to make them all until hitting the crossbar with his final attempt.

— Fielding kickoff returns from a Jugs machine during a drill were Dallis Flowers, Patrick Taylor, Corey Kiner, Ameer Abdullah and Watkins.

— A few plays before the end of practice, a scrum broke out that was mostly a lot of pushing and shoving a good distance from where the media was stationed.

— No. 3 quarterback Carter Bradley, retained at the expense of former third-stringer Tanner Mordecai, has a very quick release thrown from an almost three-quarters motion. He could see extensive action in Saturday’s preseason game against Denver.

RESTING OR REHABBING

Among those who sat out practice Tuesday:

— Bosa, although he looked plenty explosive hitting the bag before practice began. No injury disclosed.

— FB Kyle Juszczyk (bruised Achilles). The 49ers worked without a fullback for the second straight day, occasionally lining up a tight end in the backfield.

— WR Jauan Jennings (calf strain).

— DT Evan Anderson (knee bruise). Was spotted on sideline but not practicing yet.

— RB Isaac Guerendo (shoulder). Not suited up but made his way over to watch with the offense later in practice. Out “a few weeks,” according to Shanahan.

— WR Jacob Cowing (hamstring). Injured in very first camp practice. Expected back next week leading up to second preseason game against Raiders.

— CB Renardo Green (hamstring). Also expected to be back for Raiders.

— S Ji’Ayir Brown (ankle). Was working intently at nearly top speed with training staff as practice began.

— DT Kevin Givens (pectoral). Likely will begin season on injured reserve.

— DL Sam Okuayinonu (groin)

— S Siran Neal (undisclosed)

TRANSACTIONS

— The 49ers brought back wide receiver Equanimeous St. Brown and released Andy Isabella.