4:38pm: Both Mebane and Willis have now officially been placed on IR by their respective teams.
12:19pm: Two key defensive players on NFC West contenders will be sidelined for the rest of the season with injuries, according to multiple reports. Seahawks defensive tackle Brandon Mebane has suffered a torn hamstring that will end his season, tweets Mike Garafolo of FOX Sports, , who also reported (via Twitter) that 49ers linebacker Patrick Willis was likely to undergo season-ending surgery. A source confirms to Matt Maiocco of CSNBayArea.com (Twitter link) that the Niners are placing Willis, who has a toe injury, on season-ending injured reserve.
The losses are significant ones for the Seahawks and 49ers, who currently rank second and third, respectively, in a competitive NFC West division. Mebane has been Seattle’s best interior defensive lineman this season, and his absence figures to mean increased playing time for Jordan Hill, Kevin Williams, and Tony McDaniel. The Seahawks may also add another defensive tackle to their roster — the team has Jimmy Staten on its practice squad, and worked out free agent Michael Brooks today, per Aaron Wilson of the Baltimore Sun (via Twitter).
As for the Niners, while Willis will very much be missed, the team does have reinforcements on the way. Rookie Chris Borland has been excellent in an increased role over San Francisco’s last two games, and Aldon Smith was reinstated today following his nine-game suspension. NaVorro Bowman may also return within the next few weeks, assuming he doesn’t have any setbacks on his way back from last year’s knee injury.
Neither team has officially placed its injured player on IR yet, but an announcement should come soon in both cases.