49ers-Seahawks: Adrian Colbert ruled out, Trent Brown hurt shoulder in practice

San Francisco 49ers head coach Kyle Shanahan delivered some bad news on Friday, confirming that rookie safety Adrian Colbert will not be active against the Seattle Seahawks as he is not sufficiently recovered from surgery on his broken thumb. In addition to that, the 49ers have a new injury to one of their best players as right tackle Trent Brown is dealing with a shoulder issue.

The 49ers will be down to their fourth starting free safety on Sunday, probably veteran Antone Exum, though Dexter McCoil is also in the discussion. Colbert was great against the New York Giants before the bye week and some believe he could be the future at the free safety position given the uncertainty surrounding Jimmie Ward and Eric Reid, who has moved positions twice this year.

But despite the fact that the 49ers will be down to their fourth-string safety, the Brown injury is much more concerning. Brown sustained a shoulder injury at practice and is considered a game-time decision for Sunday against the Seattle Seahawks.

Brown is perhaps the 49ers’ best performer on the offensive side of the ball this season. He’s out-played everyone else on the line overall, including left tackle Joe Staley. He is the best pass-blocker on the team and seems to be improving in run blocking as the season goes on.

If they have to play without Brown for any period of time, it’s a major concern. Erik Magnuson played some tackle when the 49ers were injured recently and he looked decent, but nothing on Brown’s level.