Purdy (shoulder) has been ruled out for Sunday's game at Green Bay, Eric Branch of the San Francisco Chronicle reports.
Coach Kyle Shanahan announced Friday that Brandon Allen will be the starting quarterback for Week 12. GM John Lynch downplayed Purdy's quick departure from Thursday's practice, but Shanahan acknowledged Friday afternoon that things didn't go well during the session, noting that the level of pain in Purdy's right shoulder surprised both team and player (per David Lombardi of SFStandard.com). Shanahan hasn't commented on expectations for Purdy beyond this weekend, with the next chance to play being a Week 13 contest at Buffalo on Sunday, Dec. 1.