49ers put Chris Cook, Daniel Kilgore on injured reserve

The San Francisco 49ers have placed cornerback Chris Cook and center Daniel Kilgore on injured reserve, effectively ending their seasons. Kilgore underwent surgery on Tuesday on a fractured left leg after injuring it in the team's last game. This move isn't surprising, as it was known pretty quickly that Kilgore's injury was serious and potentially season-ending.

Cook left the game on Sunday with a hamstring injury, and his placement on injured reserve is something of a surprise. I'm not sure if the 49ers know for certain that there would be no chance he could play this season, but I have to imagine that the sheer number of injured players forced them to make the decision to not carry a fringe cornerback with a potentially long-term hamstring injury.

Tramaine Brock, Chris Culliver, Perrish Cox and rookie Dontae Johnson are the four cornerbacks on the roster, with Jimmie Ward getting in plenty of nickel work as well. Kilgore's replacement will be rookie third-round pick Marcus Martin. That could turn out well, as many expected Martin to have the job to begin with had he not been injured for the first seven games of the season.

Whatever the case, the 49ers signed special teams player Bubba Ventrone, because they're contractually obligated to do something with special teams every time they make a roster move.

What's interesting now is what happens with that final roster spot. There's been talk of a potential reduced suspension for linebacker Aldon Smith, and that spot could be open for him. He's served seven games of his nine-game suspension and the reports have suggested it could be reduced by one or two games -- so he's definitely within that window.