Countdown to Camp is a series of stories examining the Packers' roster, position by position, leading up to training camp. The seventh installment features the linebackers.

GREEN BAY – The Smith Bros. era is upon us.

The 2019 season not only marked a turning point for the Packers' defense, but it also saw Za'Darius Smith and Preston Smith emerge as two of the NFL's top up-and-coming pass rushers.

When General Manager Brian Gutekunst signed the Smiths in March 2019, he bet on potential over previous production with Preston coming off a four-sack year in Washington and Za'Darius having started only 16 combined games over four seasons in Baltimore.

It took only one game to prove the Smiths were a worthwhile investment. The two dominated in the Packers' 10-3 win over Chicago in the opener, combining for eight tackles, six quarterback hits and 2½ sacks – and never let up.

Za'Darius' gregarious personality made him an instant fan favorite. He went viral in November for wearing an undershirt in support of the mother of a member of the equipment staff who was battling cancer. A month later, he pulled the same trick again when he revealed a "Snubbed" shirt under his jersey following a sack, in response to not being voted to the Pro Bowl on initial balloting.

Za'Darius (6-4, 272), who eventually made the Pro Bowl as an alternate, set career highs across the board with 55 tackles, 37 QB hits, and a team-high 13½ sacks. His 93 pressures paced all NFL pass rushers, according to Pro Football Focus, and the most by a Packers player in more than a decade.

While not as outspoken as Za'Darius, Preston Smith (6-5, 265) was equally effective. He, too, enjoyed a career year in his first campaign with the Packers, with 56 tackles, 12 sacks and an interception.

Neither Smith missed a game all season, with both playing more than 83% of the Packers' defensive snaps (Za'Darius 872, Preston 870). Going into 2020, it's the Packers' hope to take a few snaps off their pass rushers' plates and they'll be counting on a young stable of outside linebackers to accomplish that goal.

Veteran Kyler Fackrell, the primary backup to the Smiths last year, signed with the New York Giants as an unrestricted free agent in March, vacating 415 defensive snaps in the process.

Rashan Gary, the 12th overall pick in last year's NFL Draft, is expected to see a large chunk of those snaps. The 22-year-old linebacker played primarily in the dime package his rookie year, recording 13 tackles and two sacks on 244 snaps.

Speaking with reporters earlier this offseason, defensive coordinator Mike Pettine said he had big plans for Gary in his second season. Pettine believes the 6-foot-5, 277-pound pass-rusher is cut from a similar cloth as Za'Darius Smith, with the versatility to play either inside or outside on the defensive front.

Behind Gary, rookie seventh-round pick Jonathan Garvin, Greg Roberts, practice-squad holdovers Tim Williams and Randy Ramsey, and undrafted rookie Delontae Scott will be competing for roster spots.

Garvin (6-4, 257) will transition from a 4-3 defensive end at the University of Miami (Fla.) to a 3-4 outside linebacker with the Packers. Only 20, Garvin declared early for the draft after recording 106 tackles and 12½ sacks in 32 games for the Hurricanes.

Williams (6-3, 244), a former fourth-round pick, was claimed off waivers from Baltimore last October. He played in one game for Green Bay before finishing the year on the Packers' practice squad.

There was a changing of the guard at inside linebacker this offseason, with starters Blake Martinez (New York Giants) and B.J. Goodson (Cleveland) leaving via unrestricted free agency.

The most likely candidate to step into Martinez's three-down role is seventh-year veteran Christian Kirksey, who played for Pettine when he served as the Browns' head coach in 2014-15.

The 27-year-old Kirksey (6-2, 235) started 54 of his 73 career NFL games, recording 484 tackles, 11½ sacks and two interceptions. He played in all 16 games during his first four seasons before hamstring and chest injuries limited him to only nine games the past two years.

There's an open competition for the spot next to Kirksey, with former third-round pick Oren Burks, second-year veterans Ty Summers and Curtis Bolton and rookie fifth-round pick Kamal Martin looking to carve out a role in Pettine's defense. The Packers also brought in undrafted rookie Tipa Galeai, a former teammate of first-round pick Jordan Love at Utah State.

Burks was projected to start alongside Martinez the past two summers before shoulder and chest injuries sidelined him for the start of each regular season. To date, the 6-foot-3, 233-pound linebacker has played 179 defensive snaps in 26 career games.

Summers (6-1, 241) didn't see a defensive snap during his rookie season but led Packers' special teams with 311 snaps played. Bolton (6-0, 228), an undrafted free agent out of Oklahoma, made a push for a starting job after Burks' chest injury before suffering a season-ending knee injury of his own in Green Bay's third preseason game.

Countdown to Camp series

QB: Behind Rodgers, top backup competition awaits

RB: Backfield options growing

WR: Adams continues his march into elite territory

TE: Trusting draft-and-develop process

OL: Leadership up front remains strong and respected

DL: Progress required from returnees