SANTA CLARA -- Coach Kyle Shanahan said he seeks balance on offense.

But, sometimes, there is a game such as Sunday’s against the Los Angeles Chargers, and he calls 42 pass plays on the 49ers’ 59 offensive snaps.

“We want to be able to do both. We want to attack,” Shanahan said on “49ers Game Plan,” which airs Saturday on NBC Bay Area (Ch. 3) at 7 p.m.

“We never go into a game and say, ‘Hey, we’re just going to do this,’ or ‘We’re just going to do that.’ We have a plan that you can attack both. We like to see how defenses are attacking us, and we like to come at them when they’re vulnerable.”

Running back Matt Breida entered last week’s game against the Chargers tied atop the NFL’s rushing list. He faced some challenges along the way in Week 4.

The Los Angeles defense loaded up at the line of scrimmage with an extra defender to stop the run and challenge quarterback C.J. Beathard, who was making his first start of the season in place of injured Jimmy Garoppolo.

The 49ers played most of the game with a banged-up offensive line. Left tackle Joe Staley exited with a knee injury early in the second quarter, and center Weston Richburg, right tackle Mike McGlinchey and right guard Mike Person were also slowed due to knee issues.

Moreover, Breida sustained a shoulder injury early in the fourth quarter. Breida carried nine times for 39 yards, and Alfred Morris, who is battling a knee injury, had just four attempts for 14 yards.

 

Beathard had three planned run plays, and wide receiver Marquise Goodwin carried on a reverse to account for the team’s 17 called run plays against the Chargers.

Shanahan said everything last week – including the strength of Chargers nose tackle Brandon Mebane against the run -- added up to a heavy dose of passing plays.

“It has to do with what gives you the best chance to move the chains,” Shanahan said. “What gives you the best chance to score? When teams are loaded up in the box with eight-man front, we’re not going to throw it every time versus that. . . . (But) it’s playing things off of each other. You try to get in that flow so you can set things up.”

Shanahan said just because the 49ers tilted heavily toward the passing game last week does not mean it will work out the same way Sunday if the Arizona Cardinals put an eighth defender in the box to stop the run. The Cardinals' defense ranks 31st in the NFL against the run.

“I always say, and it sounds contradictory, if you want to run the ball, you have to throw the ball,” Shanahan said. “And if you want to throw the ball, you have to be able to run the ball. You have to balance it out. I’d love to run the ball 30 times.:”

Sometimes, the best more to take pressure off a banged-up offensive line is to put them in pass protection against a defense that is strong at stopping the run. Other times, Shanahan said, if a defense is particularly effective at rushing the passer, the more reasonable option is to run the ball.

"There’s no consistent answer,” Shanahan said, “but there is an answer. It depends on what you’re going against.”