This is the sixth in a series of stories that’s examining the Packers’ roster, position by position, leading up to training camp. The series continues with the linebackers.

GREEN BAY – There’s no mystery as to who the Packers’ top two outside linebackers are, but at inside linebacker the picture is less clear, and that’s not a bad thing.

With Sam Barrington coming back from a season-ending injury, Jake Ryan entering his second season leaner and faster, and Blake Martinez arriving in the fourth round of the draft from Stanford, roles and responsibilities for the top inside ’backers are as yet undefined.

It’s conceivable defensive coordinator Dom Capers could go with one pair in the base defense and a different pair in the nickel, depending on matchups. Martinez might be best suited as the lone guy in the dime, a job Joe Thomas held last season, but time will tell.

However it shakes out, the key is to have multiple options for Capers’ different packages, which the Packers lacked last year, forcing Clay Matthews to play inside far more than desired. When Mike McCarthy announced at season’s end that Matthews would return to outside linebacker as his “starting point,” he was signaling a pending upgrade in both quality and depth inside.

Barrington proved himself in 2014 and has indicated nothing will hold him back this year. Ryan’s half-season as a starter last year pegged him as a player on the rise. Like many inside linebackers, Martinez was a tackling machine in college, and his speed brings the pass-coverage element to the table as well.

In addition to Thomas, those battling for reserve roles include former fourth-round draft pick Carl Bradford, now in the second full season of a transition from outside to inside, and undrafted rookies Beniquez Brown of Mississippi State and Manoa Pikula from BYU.

On the outside, Matthews’ return to his “natural position” puts the Packers back where they were at the start of 2014, when the idea was to pair Matthews and free-agent acquisition Julius Peppers as bookend rushers.

That lasted for only half a season before Matthews had to move inside, and while he may still rush the passer up the middle occasionally to keep protection units guessing, he won’t be plugging the run when he moves over there.

Peppers continues to defy age and conventional football wisdom by remaining so productive in his mid-30s. Last year was his ninth in 14 pro seasons with double-digit sacks, and he’s just six sacks away from reaching fifth all-time.

Capers’ choices for matchups and packages go even further beyond the top two here.

Fifth-year pro Nick Perry was brought back after his rookie contract expired, and he was healthy enough to participate fully in an offseason program for the first time in his career. Perry ended last season with borderline dominant play in the two playoff games, and he now has six career postseason sacks in just five contests, third in team history.

Jayrone Elliott enters his third season as a special-teams leader looking to become more of a regular in the pass-rush rotation. After making an impact on defense in the first month of 2015 (interception, forced fumble, two sacks in Weeks 2-4), Elliott admitted he started chasing plays and got away from assignment football at times, and some health issues slowed him down, too. It was a year he vowed to learn from.

Datone Jones continues to learn the position as well, transitioning from defensive end to a stand-up rusher with the size to slide to the interior when needed, a la Peppers. Another veteran was added in free agency in Lerentee McCray, though he was sidelined through OTAs with an undisclosed injury. As for young, developmental prospects, Utah State’s Kyler Fackrell was drafted in the third round and Arizona’s Reggie Gilbert is an undrafted rookie.

Fackrell, older than the normal rookie at 24, is coming off a bounce-back senior college season that he needed in order to get on pro teams’ radar after a torn ACL wiped out his junior year. At 6-5, Fackrell has the frame to build on his current 245 pounds as he gets his feet wet in the NFL.

Countdown to Camp series

QB: It’s Hundley’s time to shine

RB: Spotlight remains on Lacy

WR/TE: No. 3 receiver the competition to watch

OL: Offensive line depth stands out

DL: Prospects must produce on defensive line