The 49ers have not kept three quarterbacks on their initial 53-man roster since coach Kyle Shanahan and general manager John Lynch arrived in 2017.

And Shanahan seemed to imply the club will keep two at the beginning of this season, too. C.J. Beathard and Nick Mullens are competing for the backup role behind starter Jimmy Garoppolo.

“I know we have two backup quarterbacks who are both capable of starting and I would be happy with either one as our backup,” Shanahan said after the team returned to the Bay Area from its 24-15 preseason victory over the Denver Broncos on Monday night.

“One of those guys is going to win the job, and we will make that decision. I do not see myself making that decision until I absolutely have to, and that probably won’t be until the final 53.”

If the 49ers were to keep three quarterbacks on their roster, a decision on the backup would not have to be made until 90 minutes before the regular-season opener on Sunday, Sept. 8, against the Tampa Bay Buccaneers when seven inactive players must be announced.

Shanahan said he is in “a pretty good spot,” as far as determining the backup. But he said he has yet to determine who will follow Garoppolo in the preseason game Saturday night at Kansas City. Then, he said, the other quarterback likely will see the bulk of the playing time in the final exhibition game, Thursday, Aug. 24, against the Los Angeles Chargers.

 

“I feel very good with both the guys,” Shanahan said. “We’ve had both of the guys here in a lot of game situations. But it’s been a fun battle to watch. I think both of them are playing better than they have the last two years.”

Based on how both quarterbacks have performed in regular-season games, Mullens is the favorite. Last season, he averaged 284.6 yards passing – fourth-most in NFL history through eight games – with 13 touchdowns, 10 interceptions and a 90.0 passer rating.

Beathard averaged 250.4 yards passing with eight touchdowns, seven interceptions and a passer rating of 81.8. Beathard also was sacked with more frequency than Mullens.

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But Shanahan designs his offense around the big play, and that is where Beathard could have the advantage because of his willingness to sit in the pocket and let downfield routes develop.

“Every time C.J.’s in there you’ve got a chance for a big play,” Shanahan said. “He loves the big play.”

Beathard had two opportunities for big plays Monday night. He overthrew Richie James on a deep corner route to the right side, then Kendrick Bourne failed to hold onto a deep ball down the left side.

“I thought C.J. missed a couple plays early, but nothing too bad,” Shanahan said. “Then Nick came in and didn’t have many opportunities, but made the best (of them).”

Mullens and Bourne teamed up for a well-timed and delivered 1-yard touchdown on a fade route against tight coverage.