What Matthews' injury could mean for 4-3 defense

The Green Bay Packers installed a new 4-3 (or quad) defensive package this offseason to maximize linebacker Clay Matthews' versatility in coordinator Dom Capers' scheme.

But what if there is no Matthews?

On Monday, Packers coach Mike McCarthy didn't offer any update on the status of the four-time Pro Bowl linebacker, who sat out during the fourth quarter of Sunday's 19-7 loss to Detroit because of a groin injury.

Matthews told ESPN.com he thinks "it's something I can play with, but you've got to make sure you're operating at a high level."

If it's something Matthews can't play through – he's missed time before because of his hamstring – it remains to be seen how willing Capers would be to deploy his new formation without its centerpiece.

When the defense is operating out of quad, Matthews often has lined up next to the Packers' two inside linebackers. Off a few yards from scrimmage, he can either rush the quarterback or drop into coverage. According to Pro Football Focus, he dropped 19 times in his first 50 pass-rushing snaps this season but only twice in 28 snaps on Sunday.

The Packers mostly ran their nickel and dime defenses when Matthews was off the field, but reverted back to quad for two fourth-quarter plays when the base 3-4 defense was having difficulty stopping the Lions' four-minute offense.

In that particular look, Jamari Lattimore slid over into Matthews' spot on the left side of Julius Peppers with Sam Barrington re-entering next to A.J. Hawk at the traditional inside linebacker spots.

Lattimore (6-foot-2, 229 pounds) has played both outside and inside linebacker since making the team as an undrafted free agent. He played eight defensive snaps his first two seasons, but the Packers liked Lattimore for the same reason they drafted Matthews in the first round in 2009: his athleticism, length and quickness.

Lattimore became a special-teams stalwart, and the Packers liked the former Middle Tennessee State defensive end enough to give him a first-right-of-refusal restricted tender worth $1.4 million this offseason.

During the offseason program, Lattimore moved around quite a bit in Capers' defense with Matthews (broken thumb) and Nick Perry (foot/knee) sidelined with injuries.

"He works as Clay's backup in some of those (packages)," Capers said of Lattimore. "I like his athletic ability. He can make plays in space. He's a rangy guy and I think he can cover and he can blitz."

The Packers have been stretched thin at inside linebacker with Brad Jones missing the past two games with a quadriceps injury. McCarthy said Monday that Jones is progressing, but probably is a little frustrated since "it's not gone as fast he'd like."

Barrington, the Packers' seventh-round pick in 2013, played 18 defensive snaps against the Lions after playing only one during his rookie season. The only other inside linebacker under contract is rookie Carl Bradford, who started playing there in the preseason finale.

The Packers are deeper at outside linebacker than they were last year when Matthews missed six games with the twice-broken thumb, but they don't want Peppers, Mike Neal or Perry dropping into coverage more than they have to.

That's what's makes Matthews so important to the defense. He can play outside as easily as inside, though his penchant for pass-rushing his ultimately what earned him a five-year, $66 million extension last year.

Matthews might be fine, but the Packers have plans in place if he's not. Based on Sunday's small sample size, Lattimore's importance would grow considerably if Matthews misses any time this season.

"Obviously, you'd always like to have Clay because Clay factors into all those personnel groups, but you have to be smart," Capers said. "If he has a little something come up, you don't want to risk things. I'm not sure where he is."

-whodkiew@pressgazettemedia.com and follow him on Twitter @WesHod.