Jimmy Garoppolo’s torn ACL kills the momentum Kyle Shanahan’s 49ers were building

After an offseason predicated around the concept of building the team “brick-by-brick,” the San Francisco 49ers have had several bricks removed just three games into the 2018 season. The latest — and biggest — is a torn ACL that will sideline franchise quarterback Jimmy Garoppolo through the rest of the year.

Garoppolo left Sunday’s game against the Kansas City Chiefs after he made a cut on the sideline while trying to pick up extra yards while trying to lead a 49ers comeback. The knee he planted on buckled, and he took a big hit for good measure. He was eventually carted off the field, bringing in second-year quarterback C.J. Beathard to take over.

Now the team is dealing with a season-ending injury for the man they paid $137.5 million this offseason that landed him on injured reserve Wednesday.

In the middle of last season, the 49ers traded a second-round pick for Garoppolo. He wound up starting the final five games of the season, all victories for San Francisco. During the course of these wins, it was stressed by 49ers coaches that Garoppolo was using only a small portion of the playbook, and that it would take a full offseason and then some before that side of the ball would be running at full speed.

Garoppolo had his struggles through two-plus games this season. He had a couple interceptions in a losing effort against the Vikings and was sacked six times in a narrow win over the Lions in Week 2.

Against the Chiefs, Garoppolo had a few high throws and was sacked four times, but he also looked a lot better after making some halftime adjustments. He found some momentum, and a game that was 35-7 at one point was approaching a one-score game thanks to two third-quarter touchdown drives. That comeback attempt was quickly stifled by his injury. He finished the game 20 of 30 with a pair of touchdowns and no interceptions, but the Chiefs got the 38-27 victory.

Shanahan’s offense is complex, with very specific motions and personnel groupings that made him a favorite OC in Atlanta. An entire offseason was spent installing it, but with quite a few new — and young — players, the offense was expected to get better as the season progressed.

That’s looking less likely now. Beathard is a player the team likes, but he was benched for Garoppolo last season for a reason. When Garoppolo went down, so did all the 49ers’ momentum.

“I’m definitely happy with the guys we got,” Shanahan said after the injury to Garoppolo and the loss to Kansas City. He put on a brave face and the locker room immediately embraced the next-man-up mentality. But the 49ers are running out of men.

Jerick McKinnon, the team’s starting running back, was lost for the season before Week 1. Both Marquise Goodwin and Richard Sherman went into the matchup against the Chiefs with ailments, while starting safety Jaquiski Tartt missed the game entirely. Sherman was injured further during the Week 3 game, while defensive back Jimmie Ward, running back Matt Breida, defensive lineman Solomon Thomas, and right guard Mike Person all sustained injuries. Besides Garoppolo, only Sherman is expected to miss time. It’s only a few weeks due to a minor calf injury, but that still takes away one of the defense’s biggest players.

The 49ers have made some strides on the offensive side of the ball. They were 1-10 when Garoppolo took over in 2017, and finished that season at 6-10. This season, both of the team’s losses were close and hinged on a couple plays. San Francisco entered the year as a team on the rise this and one that was likely to get better as the offense jelled.

But with all of the injuries, especially Garoppolo’s, the long road to being the team that Shanahan and general manager John Lynch want just got longer.