Last year the Green Bay Packers were 12-4, won their fourth straight NFC North division title and scored the most points in the league. They made the playoffs for the sixth season in a row. They came (painfully) close to reaching the Super Bowl.

This year, the Packers return 95 percent of those high-scoring offensive snaps from last season, the most in the NFL. They bring back the defending (and two-time) MVP at quarterback, a top-tier running back, one of the league's most explosive wide receiver groups and an offensive line that's the best Green Bay's had since head coach Mike McCarthy took over in 2006.

The offense is set and stacked and should score plenty again this season.

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But what about that defense?

As the Packers open their 2015 training camp on July 30, the defensive side of the ball is where a lot of the intrigue can be found. It's not nearly as bad a unit as the 2011 version, which ranked last in the league in total defense and was the worst in NFL history in pass defense -- coincidentally, that year's team also had the league's top scoring offense, a major factor in so many yards allowed -- but there are many more question marks.

McCarthy has given up offensive play-calling duties in order to give more macro focus to the defense and special teams. His team has a middle-of-the-pack schedule (the Packers' 2015 opponents had a combined .529 winning percentage, giving Green Bay the 14th strongest schedule) but faces difficult NFC West foes Seattle (Week 2) and San Francisco (Week 4) early.

With all that in mind, let's take a closer look at McCarthy's roster as the players arrive in camp and examine some of the more important subplots.

Newcomers to watch: Cornerbacks Damarious Randall and Quinten Rollins

The Packers' 10th-ranked pass defense lost two outside cornerbacks in the offseason, veteran starter Tramon Williams (to the Browns) and versatile, physical Davon House. They also opted not to re-sign special teams ace Jarrett Bush. So there were some holes at corner. To fill them, the Packers spent their first-round (Randall) and second-round (Rollins) draft picks on cornerbacks.

But neither is a proven commodity at the position, as Randall, a former baseball prospect, played mostly safety at Arizona State, while Rollins, who was on the basketball team for four years at Miami (Ohio), only played one season of football. Still, both showed coverage ability, instincts and athleticism that led the Packers to draft them early and both could see significant action as rookies. Each player saw offseason-practice snaps at both inside and outside spots and, if fourth-year cornerback Casey Hayward's injury issues persist, one of the two rookies could be starting when the season begins.

Storyline to watch: Uncertainty on the defensive line

There are a lot of issues on the Packers' defensive front. Two players are facing suspensions to open the season -- end Datone Jones (one game for violating the NFL's substance-abuse policy) and tackle Letroy Guion (three games for an offseason arrest) -- which not only keeps them off the field, but also opens up temporary roster spots for other players. Then there's defensive tackle B.J. Raji, who in three years went from Pro Bowler to unproductive to missing all of last season with a torn biceps. He's back now, recovered from his injury, signed to a one-year contract and eager to prove himself dominant again on the line. Will Khyri Thorton, a 2014 third-round pick, show anything?

Then there are some questions asked in a more positive tone. Will Mike Daniels, a fiery and vocal leader who had 12 sacks over the past two years, become a star in his contract year and earn a Green Bay extension? Will Josh Boyd, quietly steady in his first two seasons, make a big jump in his third year? Will dark horses Mike Pennel, who was undrafted last year but played in 13 games for the Packers, or Christian Ringo, a sixth-round choice, become starting candidates, especially early in the season?

Underdog who could make the team: Guard Matt Rotheram

The undrafted rookie is big (6-foot-5, 325 pounds) and he was a highly regarded run blocker coming out of college. A four-year starter at the University of Pittsburgh, Rotheram received the highest run-blocking grade among college offensive guards in 2014 from ProFootballFocus. He had the second-fewest negatively graded plays among guards in the draft.

Rotheram got calls from numerous teams after he was not drafted, but he chose the Packers because he considered them the "best fit" and "best possible situation." Though he's not the most athletic lineman and his pass-blocking needs work, the consistent Rotheram is a road-grading mauler the Packers like a lot. Look for him to be the eighth offensive lineman on the Packers' 53-man roster.

The pressure is on: OLB Nick Perry

For Perry, a 2012 first-round draft pick, the 2015 season is crucially important. A college defensive end who was converted to outside linebacker, Perry has nine sacks in 32 regular-season games over three injury-plagued years. He played in 15 games and had three sacks in 2014, but the Packers still declined to exercise his fifth-year option, so he's entering a contract year.

After missing all of the 2015 offseason program following shoulder surgery, the Packers hope Perry will show in training camp that he can become an impact pass rusher. He thus far hasn't lived up to the high expectations of being a first-round pick, and needs to have a strong season to remain in Green Bay.

Star in the making: Davante Adams

In 2010, when the Packers won the Super Bowl, former second-round pick Jordy Nelson was the team's fourth wide receiver. By 2011, he was third. In 2012, he was second, and the last two years he's been Green Bay's No. 1 wide receiver, in terms of both position and production. In 2011, second-round pick Randall Cobb was the Packers' fifth wide receiver. By 2012, he was fourth. In 2013, he was third and last season he was No. 2, a starting wide receiver who was re-signed this past offseason to a $40 million contract.

The Packers hope the trajectory is the same for Adams, a second-round pick last year who became the team's No. 3 wide receiver. He had 38 receptions for 446 yards and three touchdowns in the 2014 regular season before busting out against the Cowboys in the playoffs, catching seven passes for 117 yards and a score. That game showed how far he'd come and the potential he had, not to mention the trust and chemistry he'd developed with Rodgers. If Adams can progress the same way Nelson and Cobb did, or perhaps even faster with more opportunities, he could become Green Bay's next star receiver.

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