The New England Patriots run a 3-4 base defense coordinated by Bill Belichick
Consistently in the top 15 for fantasy points, the New England defense finally broke through to the top five last year. A dominant Super Bowl reinforces confidence, and the only major offseason loss (DE Trey Flowers) was promptly replaced by Michael Bennett. Bill Belichick may call the plays himself after Brian Flores left for Miami and Greg Schiano resigned - a soft early schedule should smooth the transition.
The San Francisco 49ers run a 4-3 base defense coordinated by Robert Saleh
The 49ers continued to pour resources into their defensive line with the trade for Dee Ford and drafting of Nick Bosa, who join recent first-round picks DeForest Buckner, Arik Armstead and Solomon Thomas. Of course, Armstead and Thomas are shaping up as busts, while the rest of the defense is comprised of an odd mix of players that are either old, injury-prone or unproven. It's anyone's guess how this works out.
The New Orleans Saints run a 4-3 base defense coordinated by Dennis Allen
While the plethora of big plays from 2017 dried up, the Saints defense remained solid in 2018 and didn't suffer any huge losses during the offseason. There isn't any standout talent besides DE Cameron Jordan and CB Marshon Lattimore, or at least there won't be until DT Sheldon Rankins is back from a torn Achilles. Drew Brees provides frequent leads that translate to opportunities for sacks and interceptions.
The Chicago Bears run a 3-4 base defense coordinated by Chuck Pagano
The Bears signed CB Buster Skrine and S HaHa Clinton-Dix as cheaper replacements for Bryce Callahan (Broncos) and Adrian Amos (Packers), but they still have a fierce front seven and plenty of talent in the secondary. Khalil Mack, S Eddie Jackson and DE Akiem Hicks are studs, and 30-year-old CB Prince Amukamara is the oldest projected starter. New DC Chuck Pagano figures to blitz more often than Vic Fangio did.
The Baltimore Ravens run a 3-4 base defense coordinated by Don Martindale
C.J. Mosley, Terrell Suggs, Za'Darius Smith and Eric Weddle all found new homes during the offseason, but Baltimore may have the league's best secondary with Earl Thomas joining Tony Jefferson at safety behind a CB group that runs at least four or five deep. Mammoth tackles Brandon Williams and Michael Pierce should keep the front seven afloat while the blitz-happy Ravens sort things out in the linebacker corps.