The 49ers have been plagued by injuries this season, with perhaps their three most important players questionable for a Week 12 game against the Packers. Most noticeably, Brock Purdy has now undergone an MRI of his injured throwing shoulder.

Limited in practice the past two days, Purdy is questionable for San Francisco’s Green Bay trip. John Lynch said during a KNBR interview (h/t Cam Inman of the San Jose Mercury News) that the situation is “tenuous” and noted Brandon Allen would take the snaps up front Joshua Dobbs if Purdy couldn’t go.

Purdy hasn’t missed a start due to injury since suffering a UCL tear in the 2022 NFC Championship Game, establishing himself as the 49ers’ full-time starter during that span. Meanwhile, the 49ers have seen neither Nick Bosa nor Trent Williams practice this week. Bosa is dealing with the oblique injury he suffered against the Seahawks in Week 11, while Williams has dealt with an ankle problem.

Alarm bells are ringing about the All-Pro left tackle’s situation, Kyle Shanahan said (via Eric Branch of the San Francisco Chronicle) that the painkilling injection Williams received last week didn’t help. Considering how the 49ers fared without Williams last season, this becomes a central concern for a team that has fallen to 5-5 and has a Packers-Bills road stretch underway.

Williams took the pregame shot and played every offensive play for the 49ers in Week 12, but the aftermath threatens to keep him out. Williams, 36, hasn’t missed a single game this season; his absence last year points to problems if the 49ers don’t have the future Hall of Famer on Sunday. The 49ers lost to the Bengals and Vikings without Williams and began their push in the second half when he and Deebo Samuel returned to action. Williams was the NFL’s first-team All-Pro left tackle the past three seasons and used those accolades to secure a lucrative rework in August.

Bosa suffered hip and oblique damage in San Francisco’s loss to Seattle, which significantly hampered the team’s pass rush. The 49ers have relied on the dominant defenseman throughout his career, with the team’s surge from the Shanahan era only beginning when Bosa was drafted second overall in 2019. The 49ers’ only non-playoff season during that span (2020) came when Bosa suffered an injury. tore ACL in Week 2, and the team has played just one game without Bosa since recovering from knee surgery. As the team added Leonard Floyd in free agency and has been activated Yetur Gross-Matos from IR, the pass rush will be in jeopardy if Bosa can’t go.

The 49ers named Allen their backup QB to open the season despite Dobbs’ momentum earlier in the offseason. It stands to reason that a downgrade from Purdy to Allen would be noticeable, even if the 49ers’ last two QB injuries (which were Trey Lance And Jimmy Garoppolo) did not lead to steps back. Allen, 32, signed with the 49ers shortly after the 2023 draft and became their third-stringer when the team traded Lance to the Cowboys. Allen re-signed this year. Unlike the 2023 backup Sam DarnoldMaybe Allen should start at least one meaningful game.