What should we expect from the Packers, Vikings, Bears and Lions? Sky Sports take a look...
Green Bay Packers
Head coach: Mike McCarthy
Key man: Aaron Rodgers. The quarterback had a down year in 2015, shorn of some big targets and a lack of consistent running game. If the pieces fall into place he could be the league's best signal-caller again in 2016.
Major additions: Tight end Jared Cook is the main offseason signing but a fit Jordy Nelson is like having a new player on board. He and Rodgers have incredible chemistry and the Packers' season could depend on Nelson being as close to 100 per cent as possible.
Last season: The Packers lost their last two games to finish 10-6 and gave up the NFC North title to the Vikings on the last day. They performed better in the playoffs and were arguably a little unlucky not to reach the NFC Championship Game.
Prospects: Would be very surprised if there is a fall back on last season, which was decent enough anyway. They still boast a number of the best players in the division and if injuries are not quite so significant they should be back on top.
Prediction: 1st (12-4)
Minnesota Vikings
Head coach: Mike Zimmer
Key man: Adrian Peterson. Although he would have been vital anyway, the horrific injury to Teddy Bridgewater means Peterson simply has to have a great season for the Vikings to challenge. Peterson will be relied on to better the 1,485 yards he rushed for last season. He'll probably need to be nearer the 2,000 yard mark but whether he can do that aged 31 is doubtful.
Major additions: There might not be too many new starters for the Vikings but plenty is expected from wide receiver Laquon Treadwell. The first round pick is a big body and should complement Stefon Diggs very well. They will also have a new man under centre after Sam Bradford was acquired for a first-rounder in 2017 and a future fourth rounder - expensive you would think.
Last season: A three-game win streak at the end of the season, concluding with a winner-takes-all success over the Packers, saw them win the NFC North crown. But they would go out in the first week of the post-season in a 10-9 heartbreaker to the Seattle Seahawks after Blair Walsh missed a last-gasp field goal.
Prospects: The Vikings have one of the best defensive units in the NFL and they will need them to live up to that kind of talk. Expect a number of their games to be low-scoring affairs, taking pressure off expensively-acquired quarterback Sam Bradford to chase games - something he might still not be up to.
Prediction: 2nd (9-7)
Chicago Bears
Head coach: John Fox
Key man: Jay Cutler. The Bears have improved most of their constituent parts but Cutler is the man who holds it all together. Cutler impressed at times last season but is still consistently prone to making huge mental errors at just the wrong time. How he copes without offensive coordinator Adam Gase (now Miami Dolphins head coach) is questionable.
Major additions: Chicago had to upgrade their defense and will hope to have done that with the addition of linebackers Danny Trevathan and Jerrell Freeman, and tackle Akiem Hicks, in free agency. OLB/DE Leonard Floyd could contribute as well in his rookie season and hopes are high for WR Kevin White after he missed his first year through injury.
Last season: A 6-10 record was not something to remember but it is worth recalling that six of their defeats were by less than six points, or came in overtime.
Prospects: Much depends on Cutler, and whether running back Jeremy Langford is even remotely a replacement for Bears great Matt Forte, but the signs are that this is a better roster than 2015 and if they can turn around a few of their close losses, .500 is achievable.
Prediction: 3rd (8-8)
Detroit Lions
Head coach: Jim Caldwell
Key man: Matthew Stafford. The quarterback needs to get off to a much quicker start than last season when the Lions lost their first five games and were humiliated 45-10 by Kansas City at Wembley. A repeat of his second-half would be much more desirable.
Major additions: Marvin Jones comes in at wide receiver but the chances of him replicating retired Calvin 'Megatron' Johnson's numbers are slim. Linebacker DeAndre Levy returns from a season wrecked by injury as well.
Last season: They started 1-7 and finished 7-9 so project well for this season, but the off-season was not a kind one with Johnson's retirement. Defense remains a huge question mark even with Levy back.
Prospects: Stafford is going to need to have one of his best NFL seasons if the Lions are to make the playoffs, given such big questions over their running game, which is led by Ameer Abdullah who did little to impress in his rookie season. As already mentioned there have been few improvements on defense and that unit proved inconsistent at best in 2015.
Prediction: 4th (6-10)