GREEN BAY, Wis. - In the next-man-up world of the Green Bay Packers, the impact of an individual player's injury is seldom discussed. Quarterback Aaron Rodgers and his broken collarbone are an obvious exception, and outside linebacker Clay Matthews' prolonged absences – the four games he missed last season with a hamstring injury, and the four games he missed this year with a broken thumb – have been in a different category as well.
Last year, for instance, while Matthews was sidelined, coach Mike McCarthy – in a departure from the norm – said, "When Clay Matthews is on the field, we're a different defense."
It would appear cornerback Sam Shields is deserving of such consideration, too – although McCarthy wasn't ready to say so.
Shields missed last Sunday's loss to the New York Giants with a hamstring injury that evidently occurred in practice last Thursday and caused him to miss practice last Friday. This week, he missed all three practices, and after he sat out Friday, McCarthy listed him as questionable on the official injury report. He was one of four cornerbacks on the report, along with Casey Hayward (hamstring/out), Micah Hyde (groin/probable) and James Nixon (knee/out).
"Sam is having an excellent season. It's been great to watch Sam develop," McCarthy replied when asked if the defense is different without Shields. "Hey, he's missed, without a doubt. But this is kind where we are. This is the game of football. That's why you have 53 on your active roster. We need to go win the game regardless of what number, how much experience, or who's out there. That's the reality of this football team."
The reality at Friday's practice, though, was that the Packers had only seven defensive backs participating: Cornerbacks Tramon Williams, Davon House and Jarrett Bush, and safeties Morgan Burnett, M.D. Jennings, Chris Banjo and Jerron McMillian. But even if every other defensive back were healthy, not having Shields is a blow to this defense because of the player he has become.
"Sam is very important to this defense. Him and Clay are probably the two standouts right now," cornerbacks coach Joe Whitt said Friday afternoon. "But we don't have him. So I'm not going to be in a woe-is-me mentality right now. I'm going to be, ‘OK, Tramon, you just had your best game. House, when can we get y'all's best game together? Jarrett, can we get your best game? Can we get six of them in a row and get to where we need to be?' That's my mentality right now."
Nonetheless, there's no doubt that Shields, in his fourth season, has turned into a player who tilts the field – or takes half of it away.
"He's grown a lot. Just from the time we walked into the Wingate Hotel as roommates and we've been together since," said safety Morgan Burnett, Shields' closest friend on the team since the two entered as rookies together in 2010. "You just see the toughness in him, the competitive spirit he has. He's not afraid of any obstacles. He's not afraid of anyone. He wants to challenge himself every day. You can tell he wants to be the best and he wants to go against the best. As a friend and as a teammate, I look up to that and I feed off of that type of energy. You love to have a guy like Sam in the locker room."
And on the field. According to Pro Football Focus, Shields has been targeted 54 times this season and has given up 28 receptions for 439 yards. But of those, 13 completions for 264 yards came in the first two games, when PFF determined Shields was responsible for much of the yardage the Packers defense surrendered to the San Francisco 49ers' Anquan Boldin (13 receptions, 208 yards) and the Washington Redskins' Pierre Garcon (eight receptions, 143 yards).
In the seven games that followed beginning with Shields limiting Cincinnati Pro Bowl receiver A.J. Green to four receptions for 46 yards – Green enters the weekend tied for third in the NFL in receptions with 67 and second in the league in receiving yards with 1,020 – Shields allowed only 15 receptions for 175 yards, according to PFF.
Even more noticeably, teams were seldom even throwing in Shields' direction. After having 23 passes thrown at him those first two games, he had a total of 18 passes thrown his way in the five games before being inactive against the Giants.
"They've stopped," Whitt said. "Let me tell you what: Everybody talks about the lack of interceptions, but the kid is playing really good football. He's given up two touchdowns this year and both of them were earned. A.J. beat him on one and the one in the Washington game they really beat the defense. In the midst of us having a lack of interceptions and not playing as well as everybody predicted us to play, he is. He is."
Or was. Shields missed six games last season with a high-ankle sprain, and if he doesn't play against the Vikings, it will clearly weaken the defense. That much was evident against the Giants, when the Packers' defensive backs struggled with what defensive coordinator Dom Capers called the Giants' "switch routes," which left Hyde, and others, confused. Those miscommunications led to several completions, including a 35-yard touchdown by Hakeem Nicks. Hyde, who wouldn't have been playing the nickel spot had Shields been healthy (Williams would have held that role instead), also gave up multiple completions to Victor Cruz, one of the top slot receivers in the league.
"Sam is a special athlete. I think we've seen that since his rookie year as far as his speed and what he's able to do in coverage against some pretty good receivers," said Matthews, referring to how Shields played as an undrafted rookie free agent in 2010, serving as the third cornerback on the Super Bowl XLV-winning team. "Not having him out there is obviously . . . It's different when you lose one of your starters. He's out there for a reason – because he makes plays.
"That's kind of what you see with this team. Anytime you lose starters out there you definitely take a hit. But we'll never use that as an excuse."
The biggest change in Shields' game has been mentally. Having played wide receiver for his first three college seasons at Miami (Fla.), he arrived in Green Bay with 4.3-second speed in the 40-yard dash but little clue about playing defense. But veteran cornerback Charles Woodson took to him immediately. He liked the potential he saw in the kid, and knew that he lacked a defensive background.
"When I came in, ‘Wood' took me under his wings. We watched film together, and he showed me different things to watch for," Shields said in an interview before his injury. (He still texts with Woodson almost every day and talks to him every week or so, even though Woodson now plays for the Oakland Raiders.) "In practice, if he saw something I was doing wrong, he'd correct it. He was a big brother when I first came in.
"Formation recognition – that's what ‘Wood' was always good at. He'd see a formation, and knowing what down it was, what situation it was, he knew what was coming. I'm not like that yet, but it's getting better. I still have a lot more to learn watching film. But there's been plays this season, they come in, and I was seeing it, and I was saying to myself, ‘I'm getting it! I'm getting it!'"
That improvement has been obvious to Whitt in the weekly written tests he administers to all of his cornerbacks. Part of that test requires each player to diagram the correct defense based on the upcoming opponent's formation and personnel.
"When we first got here, the test he took, C was all you'd see – just where the corner was. ‘I have this guy.' That's all he worried about," Whitt explained. "Now, it looks like the playbook. He can sit and detail corners, nickel, dime, the ‘backer, the safeties – his test looks like the playbook. And it's so impressive to come from where he came from, where he literally put just Cs on there. That's a credit to him. That's nobody else. That's him detailing his work and his tests are the most detailed."
The only other time Whitt has seen tests like Shields' was in 2007, when he was the Atlanta Falcons' assistant defensive backs coach under veteran coach Emmitt Thomas and would grade the tests for the Pro Football Hall of Famer.
"His tests look like Lawyer Malloy's used to look when I gave him the test. And Lawyer, when I had him, he was a 12-year vet at the time," Whitt said. "Lawyer's was the only test that I could really compare to Sam's where it looks like a playbook."
With his improvement in fundamentals, his increased football IQ and the way he's done from being a sometimes unwilling tackler to being one of the secondary's most reliable in that department (he's missed six tackles while making 42), Shields had elevated his game to previously unseen heights before the injury.
"I think he's a true defensive player now. He still hasn't reached his ceiling, but he understands now that if he goes out there and details his work, he has a chance to go out there and cover the top-level guys," Whitt said. "And he wants that challenge. Is he going to be able to cover everybody all the time? No. There are some receivers in this league that are special. (Detroit's) Calvin Johnson is special, the guy we're going to play against in Dallas, Dez (Bryant), he's special. But Sam is not afraid of those challenges and he wants to go and show that he is worthy of it."
If he does, he figures to make himself plenty of money this spring – from the Packers or from another team. He's playing this year under the one-year, $2.023 million restricted free-agent tender after avoiding most of the offseason program in hopes of a long-term deal. When that didn't happen, Shields said he planned to simply focus on playing and not worrying about his future. Until his injury, he was doing just that. He was also staying healthy – something he said he was focused on doing.
"(Free agency) is in the back of my mind, but I can't let it just take over my game. I still have to play week-in and week-out," Shields said. "I can't keep that on my mind. I've got to let my play speak for itself.
"Always being healthy – that's a main thing. (Woodson) always preached to me how important it is to be available to stay out on the field. In this league, you know how it is – if you're hurt and can't be out there, someone else will steal your opportunity. So whatever nicks and bruises you've got, you try to take care of them and stay healthy."
Listen to Jason Wilde every weekday from 9 a.m. to 10 a.m. on "Green & Gold Today" on 540 ESPN, and follow him on Twitter at twitter.com/jasonjwilde.