Chargers can see why 49ers have confidence in C.J. Beathard, who takes over at quarterback

A Beathard will play a prominent role for the second consecutive Chargers home game Sunday.

During the Sept. 9 opener, the team welcomed back former general manager Bobby Beathard by inducting him into the franchise’s hall of fame.

This week, the Chargers intend to be as unwelcoming as NFL rules permit to Beathard’s grandson.

C.J. Beathard will start at quarterback for San Francisco and evidently bring the sort of fortitude that can result when football runs in the family.

“One of the toughest quarterbacks I’ve seen play,” 49ers coach Kyle Shanahan said. “He’s very intelligent … Our players have a ton of respect for him. I think C.J. will come in and play very well for us.”

In his first start this season subbing for the injured Jimmy Garoppolo, Beathard takes over a 1-2 team hoping for better win-loss results than he experienced last year as a rookie.

In 2017, he replaced an ineffective Brian Hoyer in mid-October and went 1-4 as the starter, completing 55 percent of his passes with four touchdowns and six interceptions.

San Francisco then traded for Garoppolo and made him the starter, a position he held until suffering a season-ending torn anterior cruciate ligament Sunday in a loss to Kansas City.

“He got thrown into a tough situation last year where he had to play before I wanted to put him in,” Shanahan said of Beathard, further explaining that the 49ers were a physically depleted group at the time.

That experience plus an ability to extend plays with his feet has the Chargers convinced San Francisco’s offense won’t look much different — or be any less of a challenge — under Beathard.

A third-round draft pick in 2017, Beathard played at Iowa with Chargers cornerback Desmond King. Last preseason, King was there when Beathard zigzagged through the Chargers for a 62-yard touchdown run.

“He’s not super fast, but he’s a competitor,” King said. “He’s a guy who’s gonna compete. That’s one thing I definitely know about him. He’s a competitive guy on and off the field, and he doesn’t mind contact.”

The Chargers opened the week not knowing a lot about Beathard, given his relative lack of NFL playing time. By Wednesday, coach Anthony Lynn was calling him “Casey,” which is Beathard’s given name.

“I’m sure he learned from his rookie season,” Lynn said. “He’ll move around a little bit. They do more things with him as far as quarterback-driven runs and things like that. So I believe he can function well within that offense.”

The 49ers, despite losing their starting quarterback not even a quarter of the way through the season, sound certain Beathard will perform better this time.

Several of San Francisco’s players have been quoted this week expressing their confidence in Beathard.

“He’s going to shock a lot of people,” running back Matt Breida told The San Jose Mercury News.

“From what we’ve seen on film, he’s a lot more comfortable than what he was last year,” King said. “They believe in him, and he’s gonna get his opportunity to play.”

Rough going

After three weeks of confusion and discontent among the players, the NFL issued a clarification Thursday of its roughing-the-passer rule, including a video tutorial distributed to each team.

The Chargers haven’t been involved in any of the incidents that have left fans and people league-wide wondering what is and isn’t a 15-yard penalty.

“I think the intent of the rule was good, so, as a quarterback, we can appreciate it,” Philip Rivers said. “As a passer, you appreciate all the protection they’ve given us. At the same time, I can certainly feel for those defenders because they’re trying.”

Injury ward

Wide receiver Keenan Allen did not practice for the second day in a row, leaving his status for Sunday in doubt. If he’s unable to play, the Chargers likely would lean more on Mike Williams.

Allen, who has been bothered by a sore knee suffered against the Rams, also was listed Thursday as having a tooth issue.

Rookie linebacker Kyzir White was an addition to the Chargers’ latest injury report. He didn’t practice because of a knee problem.

Wide receiver Travis Benjamin (foot) was a limited participant.

jeff.miller@latimes.com

Twitter: @JeffMillerLAT