For the fourth consecutive year, the Broncos will enter the season as the heavy favorites due to a stacked roster.
They aren't without question marks, however, foremost of which is Peyton Manning's ability to recapture the form he showed in the first half of the 2014 season.
The Raiders are finally building a nucleus of young talent, but are still years away from serious contention.
Our Roster Reset series will rank each team by the strength of their roster.
1. Denver Broncos
What's changed: Despite a wildly impressive 46-18 record over four years, coach John Fox was dumped in favor of Gary Kubiak, who brought along long-time defensive coordinator Wade Phillips.
The offense that broke a slew of records in 2013 will have a different look, as veteran Owen Daniels and second-year wideout Cody Latimer are slated to replace Pro Bowl tight end Julius Thomas and slot machine Wes Welker, respectively.
Outside of the losses of run-stuffer Terrance Knighton and free safety Rahim Moore, the defensive personnel remains largely intact. The big change is the shift from Jack Del Rio's 4-3 defense to Phillips' 3-4 scheme. Unlike most teams, the Broncos' personnel is already well-suited to the new system.
What's next:
2. San Diego Chargers
What's changed: The prospect of a franchise move to Los Angeles has Philip Rivers spooked, leaving the Chargers with one of the offseason's most intriguing decisions. Although the team's stated preference is to secure Rivers' future via a long-term deal, Oregon's Marcus Mariota looms as an interesting alternative.
If Rivers stays, he will be throwing to a pair of new targets in veteran wide receivers Stevie Johnson and Jacoby Jones.
Even with the addition of jumbo guard Orlando Franklin, pass protection remains a question mark following the retirements of veterans Nick Hardwick and Jeromey Clary and the release of guard Chad Rinehart.
The backfield is similarly in turmoil after early-down hammer Ryan Mathews landed in Philadelphia.
What's next:
3. Kansas City Chiefs
What's changed: Shortly after conceding that a historically inept receiving corps needed to be reconstructed, general manager John Dorsey dumped the trio of Dwayne Bowe, Donnie Avery and A.J. Jenkins. He succeeded in recruiting Jeremy Maclin as Bowe's replacement, reuniting the former Eagles receiver with Andy Reid.
Now that veteran Anthony Fasano has been released, promising third-year tight endTravis Kelce is expected to play a featured role in the revamped aerial attack.
The offensive line has a new look as well. After center Rodney Hudson defected to Oakland, the Chiefs responded by trading for guard Ben Grubbs and signing Paul Fanaika. It remains to be seen if this unit is an upgrade on last year's, which struggled to maintain consistency.
What's next:
4. Oakland Raiders
What's changed: Gone are interim coach Tony Sparano, offensive coordinator Greg Olson and defensive coordinator Jason Tarver, replaced by Jack Del Rio, Bill Musgrave and Ken Norton Jr.
The high-dollar signings of center Rodney Hudson and blocking specialist Lee Smith suggest Musgrave plans to run a smash-mouth attack to complement second-year quarterback Derek Carr.
One year after the Raiders signed a bevy of over-the-hill veterans to bolster the defense, the majority were jettisoned in favor of another batch of free-agent additions headlined by nose tackle Dan Williams, middle linebacker Curtis Lofton and safety Nate Allen.
General manager Reggie McKenzie desperately needs a second consecutive strong draft haul so he can put a halt to Oakland's annual parade of free-agent disappointment.
What's next:
The latest Around The NFL Podcast previews the 2015 NFL Draft and breaks down the biggest rumors and storylines. Find more Around The NFL content on NFL NOW.