C.J. Beathard’s iffy health status could make 49ers’ QB decision easy

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Kyle Shanahan’s quarterback decision might be made for him this week.

On Monday, the 49ers’ head coach said rookie C.J. Beathard was “pretty banged up” after he absorbed a knee contusion and a hip strain in the 24-13 loss to the Seahawks on Sunday that forced Jimmy Garoppolo to make his three-snap 49ers’ debut.

Shanahan indicated he wasn’t sure Beathard would be able to participate in the team’s first practice Wednesday in advance of a visit to Chicago on Sunday. Shanahan also said he would announce his starter Wednesday, partly because his first-string QB will need to take all the first-team practice snaps before Sunday’s game.

Beathard “is a rookie quarterback and (Garoppolo) basically is also, with him just being here,” Shanahan said. “To give those guys the best chance to be successful, you want to give them all the reps, which still isn’t enough reps. Anytime you split those evenly it’s kind of a disservice to both.”

Even if Beathard was fully healthy, it might be a logical time to insert Garoppolo, who was acquired in a trade from the Patriots on Oct. 30 and has spent his first three games as Beathard’s backup.

Shanahan said Beathard remained the starter against the Seahawks partly because of his impressive performance in a 31-21 win against the Giants on Nov. 12. However, Beathard, who ranks 34th in the NFL in passer rating (69.2), didn’t duplicate that start against Seattle, completing 22 of 38 passes for 201 yards with an interception.

On Sunday, Garoppolo capped his three-snap debut by rolling left and throwing a 10-yard touchdown pass to Louis Murphy as time expired.

Garoppolo completed 2 of 2 passes for 18 yards and added a 4-yard run. Shanahan said on his first pass, an 8-yard completion to Aldrick Robinson, he “hit a guy perfect in rhythm” before he made an “off-schedule” play on the scoring pass.

Jimmy Garoppolo (l to r), 49ers quarterback, and C.J. Beathard, 49ers quarterback practice with teammates at the Levi's Stadium practice field on Thursday, November 2, 2017 in Santa Clara, Calif. Jimmy Garoppolo (l to r), 49ers quarterback, and C.J. Beathard, 49ers quarterback practice with teammates at the Levi's Stadium practice field on Thursday, November 2, 2017 in Santa Clara, Calif. Photo: Lea Suzuki, The Chronicle Buy photo Photo: Lea Suzuki, The Chronicle Image 1 of / 1 Caption Close C.J. Beathard’s iffy health status could make 49ers’ QB decision easy 1 / 1 Back to Gallery

“He’s gotten better — it’s still a work in progress,” Shanahan said of Garoppolo’s grasp of the offense. “It will continue to be throughout the year. Hopefully, he’ll be a lot more comfortable going into next year.”

Beathard presumably will be healthy enough to play, but he also has taken a hellacious beating this season. On Sunday, he was dropped for three sacks and took 13 more hits, bringing his totals to 17 and 52, respectively, in his five starts.

He was injured against the Seahawks when defensive end Michael Bennett jumped offside and hit him around his left knee.

“It was pretty violent, right in his knee area,” Shanahan said. “I’m sure that jarred something into his hip that went into his whole body. He hit his head pretty hard at the end of it, too. He fell pretty hard.”

Of course, the 49ers don’t want Garoppolo, who they hope is their franchise quarterback, to endure the pounding Beathard has endured. Starting right tackle Trent Brown is dealing with a shoulder injury that sidelined him against the Seahawks and undrafted rookie Darrell Williams Jr. likely would make his first career start against Chicago if Brown misses a second straight game.

However, Garoppolo is known for having a quick release. Beathard has invited some of his punishment with deliberate decision-making, understandable for a rookie, and an admirable willingness to hang in the pocket and take blows.

Shanahan was asked if Beathard has held on to the ball too long.

“There’s not an absolute answer there,” Shanahan said. “I think C.J. has done a very good job of not watching the rush. He does a good job of keeping his eyes downfield and trying to get the ball to the right places. I think he’s gotten better at that each week.”

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch