Winborn originally injured his knee in a Sept. 22 victory over Washington. Team doctors determined at that time that he would not require surgery, instead opting to let ligament damage heal on its own. He was expected to miss 4 to 6 weeks.
But when Winborn still was experiencing problems with the knee after sitting out the next 11 weeks, he underwent arthroscopic surgery Dec. 10 with the hope he'd be able to return to action this week. But after returning to practice last Thursday - and looking crisp while participating in drills - Winborn had a setback when he experienced soreness again the next day.
"He felt good one day in practice and the next day he felt that maybe it wasn't right," 49ers coach Steve Mariucci said Thursday. "We're not going to force the issue right now."
When asked if perhaps the team had miscalculated from the start an injury that was supposed to keep Winborn out not much more than a month, Mariucci said, "The doctors felt that it was in his best interest to rehab and rehab and try to get back on the field without surgery, based on their experience with that type of injury in the past. After several weeks of real slow recovery, they felt that if there was going to be any chance of him playing in the playoffs that they would do the surgery and see if it would be in time for the playoffs. That's what they did. It was successful. It's just not enough time for him to let that calm down."
The Niners ran out of time waiting for Winborn to recover, and apparently didn't feel he'd be ready to help them in the next few weeks if they are able to get past the Giants. The team had kept Winborn on the 53-man roster since his injury.
Winborn's injury created a void in San Francisco's defense that the Niners have had problems filling since he left the lineup. He's the team's best cover linebacker and also had been ferocious against the run, leading the team with 28 tackles in 10 quarters of action before he was injured.
Winborn was particularly tough against the Giants in the Sept. 5 season opener, recording a game-high 16 tackles to lead the Niners to a narrow 16-13 victory. Winborn was the best player on the field that night, when he also recorded a sack and knocked down a pass in coverage. He helped the Niners stuff Giants' star running back Tiki Barber, who was limited to just 29 yards on 15 carries. New York had only 43 yards rushing as a team.
"We've missed him all year, obviously," defensive coordinator Jim Mora said. "The guy is a great play-maker for us. You saw what he could do early this year before he got hurt. But we've also been able to compensate. Our philosophy isn't who don't we have. It is who we do have. Fortunately, we have a pretty good crew of linebackers when you look at Jeff (Ulbrich) and Derek (Smith) and Julian (Peterson). Sure, we'd love to have Jamie. But those guys will be great."