49ers not close to mastering Shanahan’s complex run game

San Francisco 49ers running back Kapri Bibbs runs before a preseason NFL football game against the Denver Broncos Saturday, Aug. 19, 2017, in Santa Clara, Calif. (AP Photo/Eric Risberg) San Francisco 49ers running back Kapri Bibbs runs before a preseason NFL football game against the Denver Broncos Saturday, Aug. 19, 2017, in Santa Clara, Calif. (AP Photo/Eric Risberg) Photo: Eric Risberg, Associated Press Photo: Eric Risberg, Associated Press Image 1 of / 7 Caption Close 49ers not close to mastering Shanahan’s complex run game 1 / 7 Back to Gallery

In his first 11 NFL seasons, 49ers left tackle Joe Staley has had seven head coaches and eight offensive coordinators, stunning figures that suggest he’s seen every conceivable X and O.

On Wednesday, however, Staley said he’s never experienced anything quite as intricate as head coach Kyle Shanahan’s rushing attack.

“I think one of the things that even I wasn’t expecting was how detailed you have to be in everything as far as the run game,” Staley said. “Aiming points. Everyone’s got to be on the same page — running backs, linemen, receivers, everybody, for it to work. That’s going to come and, hopefully, we do a better job of that this week.”

Indeed, the 49ers are in a race to get their run game going before their Sept. 10 season opener.

In two preseason games, the 49ers running backs are averaging 2.6 yards on 11 carries behind the starting offensive line, with 10 of those attempts coming from Carlos Hyde.

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It’s often said an offense can work only if all 11 players are in sync. But Staley suggested that typically isn’t true in many offenses.

“There are certain plays (in other offenses) that are dialed up for two to three guys to make their blocks, and (those plays) are usually pretty successful,” Staley said. “But what makes his so successful, a consistent top-10 offense, is the level of detail every person has. … The level of detail, everybody being on the same page, is what separates his.”

Before Staley spoke, Shanahan addressed reporters and hit on the same themes. Shanahan highlighted two runs by Hyde in Saturday’s preseason loss to the Broncos. One run gained 1 yard. The other netted 7 yards.

What made the second play successful?

“It wasn’t much of a difference — it was one step by one player,” Shanahan said. “That’s what football is about that not everyone realizes — it takes 11 guys to execute a play. Usually, the guy who has the ball in his hand is the guy who is rewarded or blamed, but I’ve been happy with Carlos’ reps in the preseason. I definitely want to do better.”

Shanahan has also been pleased with his starting offensive line’s pass protection — quarterback Brian Hoyer hasn’t been sacked — but he’s offered no such praise for its run-blocking.

Given the run-game complexity, it’s no surprise that the 49ers are off to a slow start in the preseason. But there are also questions about their personnel.

Staley, right tackle Trent Brown and center Daniel Kilgore are holdovers who started throughout training camp. Meanwhile, there are questions at both guard spots.

Left guard Joshua Garnett, a 2016 first-round pick, isn’t expected to be ready for the season opener after undergoing knee surgery and he was replaced by Zane Beadles after he was sidelined in training camp. Beadles, 30, has started 96 straight games, but has never been in an outside-zone scheme. He was almost exclusively with the second-team until Garnett was sidelined.

Brandon Fusco, 29, was released by the Vikings in February with three years remaining on a five-year, $25 million extension he signed in 2014. The 49ers signed him in May on the heels of what Fusco has acknowledged was a mediocre final season in Minnesota.

“Coming from Minnesota and coming here, I want to re-establish my career and get back on the right track,” Fusco said. “There’s a reason why I was a free agent and got picked up.”

Fusco hopes to get reestablished by helping the 49ers establish a complex rushing attack that could take a season to master.

Consider: In 2015, Shanahan’s first season as the Falcons offensive coordinator, Atlanta ranked 19th in rushing (100.4 yards per game) and 25th in yards per attempt (3.8). Last year, they were fifth both rushing (120.5) and yards per rush (4.6).

As for the 49ers, it remains to be seen how quickly they will pick up Shanahan’s system. The certainty: They aren’t there after two preseason games.

Said Staley: “We’ve got stuff to work on there.”

Briefly: The 49ers signed defensive tackle Sen’Derrick Marks to a one-year deal. Marks, 30, a 2009 second-round pick with 61 career starts, has made just three starts the past two seasons and was released by the Jaguars in March. … Safety Jimmie Ward was activated from the physically unable to perform list, where he was placed after sustaining a hamstring injury during a conditioning test July 27. … Defensive linemen DeForest Buckner (ankle), Aaron Lynch (ankle) and Ronald Blaier (groin) returned to practice.

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