San Francisco 49ers

49ers are shutting down two promising offensive weapons for season finale against Rams

The 49ers will be without two of their most promising young offensive players when they close the season against the Los Angeles Rams on Sunday.

Running back Matt Breida (ankle sprain) and rookie receiver Dante Pettis (knee sprain) won’t see the field again until 2019, coach Kyle Shanahan said Monday.

The news came as no surprise after the two left Sunday’s loss to the Chicago Bears in the second quarter. Breida has dealt with his injury since September.

Pettis sustained a knee injury on a punt return against the Chargers in Week 4, which slowed his rookie campaign until becoming the team’s most productive receiver over the past month. Shanahan said Pettis sprained his MCL.

Breida will finish his second NFL season with 814 rushing yards while averaging 5.3 yards per carry, fifth among qualified rushers.

“Matt’s had a very impressive season,” Shanahan said of Breida, noting he “started out great” after starter Jerick McKinnon sustained a torn ACL a week before the opener. “And I think Matt stepped in right away and played like a number one back. ... He got hurt early on, and he battled every week to get in there and play for us.”

With a healthy Breida next fall, Shanahan has high hopes for San Francisco’s running game with the expected return of McKinnon. Shanahan is also excited about the return of Raheem Mostert, who broke his arm in early November during a four-game stretch in which he averaged 8.9 yards per carry while filling in for Breida.

“We learned a lot about a lot of our running backs this year,” Shanahan said. “Not just Breida, but also Raheem. We went into this year just with Raheem mainly as a special-teams guy. The games that he played in, where he got a go at running back, he did a hell of a job.”

Pettis leads San Francisco with five touchdown catches. He’s second on the team in receiving yards (467) behind Pro Bowl tight end George Kittle (1,228). The second-round pick from Washington logged 371 yards and four touchdowns over his past six games.

Marquise Goodwin, the team’s starting “X” receiver, spent two weeks away from the team to deal with a family matter, which led to an increase in Pettis’ snaps. His recent play indicates he’ll be a key component in 2019, when Jimmy Garoppolo is back under center.

Shanahan, who admitted in recent weeks to being tough on the rookie, was asked what led to Pettis’ late-season surge in production.

“I think he just truly had go through it to understand the urgency of the NFL and just all the stuff that you have to go through to get open on a route,” Shanahan said. “Dante’s had success everywhere he’s been before. I know he expects to have it at the NFL level, too. I think it takes a while for a guy to learn maybe why he isn’t having (success).

“Dante’s a hard worker. He does everything you ask. But I think it took some time to realize hard you got to go on every single route. How exact you have to be with your technique with your feet, how aggressive your hands have to be.”

Veteran Pierre Garçon, 32, isn’t a lock to return next season. He was shut down this month to have arthroscopic knee surgery, which could mean the 49ers rely heavily on Pettis to improve.

“Hopefully, (Pettis) learned a little bit of the success he can have the harder he goes. He’ll take that into his offseason,” Shanahan said. “... He’s going to get better or worse, and we’re going to need him to get better and we need him to get better every day. As long as he works, I think he will.”

Shanahan also said tight end Garrett Celek (concussion), Goodwin (bruised calf) and defensive back K’waun Williams (knee) will be re-evaluated before practice Wednesday.

The players were given Monday and Tuesday off for Christmas. Coaches spent Monday at the facility to prepare the game plan before spending Christmas with their families.