Success this time of year is as much about which teams are healthiest as anything else. Just ask the Bears, who were rolling toward a playoff spot before losing Jay Cutler and Matt Forte. They suffered another key injury Sunday, in a crushing loss to Seattle.
But the injuries are mounting across the board, no surprise considering how important each game is right now.
SI.com injury expert Will Carroll is back to help diagnose some of Sunday's key injuries.
• Johnny Knox, WR, Bears (back): Knox suffered one of the scarier injures of the entire 2011 season when he was bent backwards by Seattle's Anthony Hargrove while the two players were scrambling to recover a fumble. Knox was taken to the hospital after staying on the field for several minutes and will undergo back surgery Monday.
Carroll: Knox's injury was just flat scary. The pictures look ... well, just don't look. His core may have saved his life, keeping him *just* stable enough that all that happened was a fractured lumbar vertebrae. That's bad, but he has feeling in all of his extremities. When teams start talking about "quality of life," you know how bad it is. He's done for the season, but it looked so much worse.
Carroll: Ballard went down with a knee injury and it didn't look good. It's hard to diagnose a knee from just a replay unless it's clear, but the Giants said this was a sprain. He'll have an MRI Monday and the Giants have to be hoping for a low grade sprain and an intact ACL.
Who takes Ballard's spot?: Travis Beckum would be the backup option, but he missed Sunday's game with a chest injury. If neither Beckum nor Ballard can go in Week 16, the Giants will have to come up with another option.
• Derek Sherrod, OT, Packers (leg): Are the Packers ready to start resting people for the postseason yet? One week after Greg Jennings left a game with a knee injury, Green Bay lost Bryan Bulaga to a leg injury, then saw his backup, Sherrod, carted off.
Carroll: The Packers lost more than a game. Sherrod was rolled up and broke his lower leg. It's unclear whether it's the tibia, fibula or both, but even "just" a fibula fracture would make Sherrod returning for the playoffs very difficult.
• A.J. Green, WR, Bengals (shoulder): Green came out of Sunday's game twice after slamming his shoulder into the turf in St. Louis. He still caught six passes and sounded after the game like he'll be OK for Week 16.
Carroll: Early reports had rookie sensation Green with a Grade III shoulder sprain. That's the highest degree of sprain and usually indicates a rupture -- which usually requires surgery. Green says he's going to play, so it's either not that bad or it's so bad that he can't do any more damage. It will be interesting to see how this plays out over the next few days.
Who takes Green's spot?: There's no one on the Bengals' roster capable of providing the type of impact Green does, which is why the rookie WR has been such a revelation this year. Andrew Hawkins could see some extra targets if Green has to sit.
• Willis McGahee, RB, Broncos (leg): Denver's offense started hot Sunday, but McGahee limped off after suffering an injury on a 29-yard carry to open the Broncos' second drive. He returned but had just two carries after that.
Carroll: The Broncos are just calling it a "leg injury," but all signs point to McGahee having a left hamstring strain. If so, it's the same hamstring he had issues with in mid-November and points to a recurrent problem.
• Andre Carter, DE, Patriots (leg): Carter had to be carted off after injuring his quad in Denver. Reports from Sunday night indicated that Carter would need surgery to repair the damage, meaning his season might be over. He'll go for an MRI before any decisions are made.
Carroll: While Tim Tebow laid hands on him after his injury, the healing apparently didn't take. Carter has a knee sprain and is headed for an MRI once the swelling comes down. While the ligament sprain is unknown at this time, there's not much time to come back. A low grade sprain would keep the playoffs open for Carter.
Who takes Carter's spot?: It's a tough loss for an up-and-down New England defense -- Carter is the group's best pass rusher. We'll see more of Mark Anderson going forward, unless Carter's injury is not as bad as first believed.
Carroll: Williams may need surgery to fixate things. He's done for the season and will have a tough comeback given his lack of speed.
Who takes Williams' spot?: If there's good news for Seattle here, it's that Williams has not been a very key component of the offense, falling behind Golden Tate, Ben Obomanu and Doug Baldwin in the pecking order.