It’s been the story of the Green Bay Packers’ defense all season – find someone to plug a hole created by an injury, and not only survive with the substitutions, but figure out a way to thrive.

Sure, the Packers placed three defensive starters on the NFC Pro Bowl squad in cornerback Charles Woodson, safety Nick Collins and outside linebacker Clay Matthews, and three other defenders were named Pro Bowl alternates in cornerback Tramon Williams, nose tackle B.J. Raji and inside linebacker A.J. Hawk. There’s been plenty of top-notch talent on that side of the ball.

But NFL coaches spend hours grinding tape to find weaknesses. If they exist, they’ll be exploited. No one can hide in the NFL, especially fill-ins, who can expect to be targeted and attacked.

Yet here the Packers sit, entering the playoffs with a defense ranked No. 2 in the league in points allowed (15.0) and No. 5 in the league in yards allowed (309.1) despite an injury list that could cripple most units.

Three of the Packers’ opening-day defensive starters were on injured reserve by midseason while three others missed the combined equivalent of eight games. Seven other defenders classified as key reserves have also gone down at one point or another, missing anywhere from three to 15 contests each.

“Every year is challenging – we’ve just had a little bit more change this year than you normally have,” defensive coordinator Dom Capers said. “You spend all these hours and time planning and everything and you know how you’d like things to go, but that’s just not how this game works. It doesn’t make any difference. In any game, you prepare and you have an idea of how you want the game to go, and you have to adjust sometimes and let your instincts take over and adjust on the fly. We’ve had to make quite a few adjustments.”

Head Coach Mike McCarthy mentioned earlier this week that the roughest stretch injury-wise came during Weeks 5-6, when the Packers lost back-to-back overtime games to Washington and Miami to fall to 3-3. He commented that it was “depressing” to meet with the medical staff during that time.

But since then, the Packers have gone 7-3 with a defense that has needed reinforcements from two (until now) career backups in safety Charlie Peprah and inside linebacker Desmond Bishop, a rookie seventh-round draft pick in end C.J. Wilson, a former sixth-round draft pick who didn’t initially make the team out of training camp this year in end Jarius Wynn, a non-drafted rookie in linebacker Frank Zombo (who is now injured himself), a former practice-squad player in linebacker Robert Francois, and two street free agents in end Howard Green and outside linebacker Erik Walden.

The Packers will take the field on Sunday in Philadelphia with all of those players, minus Zombo, either starting or playing a key role in defensive rotations. The only saving grace is that the injuries on defense have been so constant throughout the year, all of those players have needed to play extensively and contribute before reaching this bigger stage.

“We’re not even worried about it,” Woodson said. “We feel like whoever we have, whoever we go in with, then we’re fine, and I think that’s the way we’ve played all year. Guys have gone down week after week, but whoever we’ve gone into the game with, they’ve gone in and done their job.

“For us, we’re not worried about who may play or who might not play. Whoever’s ready, that’s who we’re going with, and we’ll feel confident with whoever’s that guy.”

That confidence stems from what those players have accomplished over the last 10 games. Here’s a detailed, game-by-game rundown of their contributions:

Week 7 vs. Minnesota – Wilson posts a career-high nine tackles, and helps make the play of the game along with Bishop. In the third quarter, Vikings quarterback Brett Favre begins to scramble to buy some time, and Wilson closes in and dives at Favre’s midsection. The pressure forces Favre into an errant throw that Bishop intercepts and returns 32 yards for a touchdown.

Wynn adds a sack of Favre on Minnesota’s final drive, forcing the Vikings to use their second timeout with just over a minute left. The Vikings fail to score and the Packers win, 28-24.

Week 8 vs. N.Y. Jets – Green, claimed off waivers from the Jets just four days before the game against his old team, spends a lot of extra hours with defensive line coach Mike Trgovac to learn as much of the run defense as he can. One of the study sessions is even in the team hotel the night before the game, using chairs in a meeting room to represent players and formations. Green then posts a season-high four assisted tackles as the Packers hold the Jets’ ground duo of LaDainian Tomlinson and Shonn Greene to a combined 76 yards on 22 carries.

Peprah helps seal the 9-0 shutout victory with two key pass break-ups in the fourth quarter on throws intended for receiver Jerricho Cotchery, both deep down the field into Green Bay territory in the final five minutes with the Packers leading just 6-0 at the time.

Week 9 vs. Dallas – Bishop and Wilson both notch sacks while Bishop and Peprah each add tackles behind the line of scrimmage as the defense dominates again, holding the Cowboys to just one touchdown in a 45-7 rout.

Week 11 at Minnesota – Following the bye, Zombo records what at the time is a career-high eight tackles in another blowout, 31-3.

Week 12 at Atlanta – Zombo outdoes himself with a career-best 11 total tackles and eight solos, including an 11-yard sack, but the Packers lose by a field goal at the gun.

Week 13 vs. San Francisco – Again Zombo shows up, getting his fourth sack of the season and getting his hands up to deflect a pass. The ball is still caught by receiver Michael Crabtree, but Peprah is there to bring him down for a 1-yard loss. The defense allows just three points in the second half as the Packers pull away to a 34-16 win.

Week 14 at Detroit – Peprah snags his first career interception as part of a defensive effort that holds the Lions to just a touchdown, but the Packers fall 7-3.

Week 15 at New England – Bishop posts a sack and forced fumble against quarterback Tom Brady and Walden nearly ends Brady’s interception-free streak with a diving attempt to pick off a pass near the goal line. Green chips in with a tackle for loss on running back BenJarvus Green-Ellis on another goal-line sequence that nearly results in a key stop when the defense only got 4 yards of field to defend following a long kickoff return. Unfortunately, the Packers come up short again, 31-27.

Week 16 vs. N.Y. Giants – Francois gets his first NFL start with the Packers needing a win to stay in the playoff hunt, and he is credited with two tackles and two quarterback pressures. He also holds his own against the run as the Giants’ duo of Brandon Jacobs and Ahmad Bradshaw produces just 78 rushing yards.

Late in what turns into a 45-17 victory, Wilson gets the pressure and quarterback hit on Eli Manning that leads to an interception for Hawk, one of six turnovers for the defense on the day.

Week 17 vs. Chicago – The pinnacle of these fill-in efforts is reached by Walden, who stayed late multiple nights with position coach Kevin Greene through late October and early November to learn the defense. He ultimately earns NFC Defensive Player of the Week with a career-best 16 tackles (12 solo) and the first three sacks of his career. Green helps him with good pressure on one of the sacks, Wynn shares a half-sack with Hawk, and Peprah grabs a key interception in the end zone to thwart a major scoring threat by Chicago as the Packers win 10-3 and qualify for the playoffs.

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In the playoffs, more of the same is needed of course. And not just needed, but expected.

One of the main reasons the defense has succeeded throughout all the personnel changes and adjustments is that the seasoned veterans and Pro Bowlers have not just tolerated the newcomers, they’ve trusted them.

It would have been easy for the proven players in Capers’ defense to feel compelled to do more, to pick up the slack. But that kind of over-reaching is precisely the type of behavior that can make a defense like Capers’ dysfunctional, because so many different parts are relied upon to do specific jobs, be it gap control, communication, and the like. Capers said everyone on defense has remained accountable to one another, and that’s what has made this work.

“I think the new guys going in, they get a feel from the veterans that if they’re going to be out there, then they’re going to depend on them,” Capers said. “I’ve always believed that it’s human nature – if you know somebody’s counting on you and they believe in you, then you in turn believe in them. That’s what you have to have. You have to have that unselfish attitude and belief in each other that gives everybody confidence you can go out and perform at a high level.”

The success of the defense amidst all the trying circumstances also has fostered even greater confidence in Capers from his players. That was bound to happen to some extent in the second year of his system, but when the unit can perform like it has in two must-win games to close the regular season when the personnel on the field is barely half what was envisioned four months ago, it speaks volumes of the schemes and game plans employed.

“A hundred percent (we) believe in everything he’s calling,” veteran defensive end Ryan Pickett said. “There’s nobody ever questioning what he’s calling. We believe in him. He’s proven. Everything we’ve been doing this year, he’s been plugging guys in and we’ve still been able to maintain our dominance on defense. So we totally have 100 percent confidence in whatever Coach Capers calls.”

All that’s left now is to carry that belief, confidence and success over to the postseason, which this year is like an extension of the last two weeks.

Many of these Packers have had to fight and claw just to get a job in the NFL, and when they got their chance, they maximized on it. The playoffs present a chance of a different sort, for everyone involved.

“We want it bad,” Woodson said. “We work hard to put ourselves in this position despite those injuries. The guys that have come in and had to play, had to step up, they’ve done a great job of having themselves prepared to play. These are guys who weren’t expected to contribute, but they’re contributing.

“Everybody’s hungry, and we have an opportunity to go in here and make some noise, and we look forward to the challenge.”

Additional coverage - Jan. 7