Of the eight teams that won a division title in 2020, only four were able to successfully defend it in 2021.

In the NFL, sustained success can be an elusive beast.

Given the seismic shifts that took place this offseason, repeating as a division champion isn't going to get any easier. Several teams made win-now moves through free agency, trades and the draft that have upped the ante.

Of course, not all divisions are created equal. The AFC West officially became a gauntlet with Russell Wilson, Davante Adams, Khalil Mack and J.C. Jackson all moving into the division, while the NFC North largely remains a one-team show.

Here, we'll rank each 2021 division champion based on the likelihood they repeat given the improvements they've made, along with the expected improvement from their division counterparts.

8. Tennessee Titans

The Tennessee Titans emerging from the regular season as the top team in the AFC was a statistical anomaly.

Mike Vrabel has to be given credit for a phenomenal coaching job, but the Titans had the lowest DVOA of any No. 1 seed since 1983, per Football Outsiders. They finished 19th in the advanced metric that measures success on a play-by-play basis.

For comparison, the Colts—who missed the playoff after an inexplicable loss to the Jaguars in Week 18—finished 11th.

Now consider the difference in the offseason the two teams just had. The Titans traded one of their best offensive weapons in A.J. Brown, leaving Ryan Tannehill with a receiving corps of Robert Woods, Treylon Burks and Nick Westbrook-Ikhine.

Derrick Henry's workload caught up with him last season. The foot injury that cost him the back half of the 2021 season should have the Titans thinking twice about how much he can handle going forward.

Again, they won the division in spite of that injury and various injuries to Brown and Julio Jones. But, statistically, it's difficult to sustain that level of winning when the team wasn't all that efficient.

The addition of Matt Ryan on the Colts should make them the favorites to win the division this season.

7. Kansas City Chiefs

The Kansas City Chiefs have won the AFC West for six consecutive seasons. Considering the events of the offseason, that streak is going to be more difficult to continue than ever.

The Chiefs are still a contender to be sure. The presence of Patrick Mahomes is going to make that true for the foreseeable future.

But Mahomes and Co. now have to navigate the toughest division in football, and they'll have to do it without their most dynamic weapon in Tyreek Hill. The deal that sent Hill to Miami brought back a good haul in draft capital, but it leaves the Chiefs with things to figure out on offense.

This ranking is more about the competition they'll see in the division, though.

The Chargers are an intriguing Super Bowl contender. Justin Herbert's continued development paired with a defense that added Khalil Mack and J.C. Jackson should see them build on their 9-8 campaign last season.

The Raiders—who finished just two games behind the Chiefs in 2021—added Chandler Jones and Davante Adams while inserting Josh McDaniels as their head coach.

Then the Broncos went and upgraded from Drew Lock and Teddy Bridgewater to Russell Wilson.

The margin for error in the division is going to be razor-thin, even for a team as good as the Chiefs.

6. Cincinnati Bengals

This ranking is not an indictment of the Cincinnati Bengals. They are, after all, the reigning AFC champions and were probably a year ahead of schedule given how bad the offensive line was at times last season.

The AFC North crown has been notoriously difficult to hang on to, though. The division has had three winners in three seasons, and no one has won it more than twice in a row since the Steelers in the mid-'90s.

Buried in the buzz from last season's playoff run is the Bengals won the division by the smallest margin possible, beating out the Steelers by half a game at 10-7. The North was the most competitive division, with the last-place Browns and Ravens finishing just two games behind the champions.

The Ravens' second-half collapse undoubtedly aided the Bengals' division title. Baltimore started the season 8-3 before a series of injuries, including an ankle injury for Lamar Jackson, became too much and they ended the season on a six-game losing streak.

With Jackson healthy, the Ravens are actually the slight favorite to win the division over at DraftKings.

The Bengals are getting some help from the other teams' quarterback situations. The Steelers are a lot less scary with either Mitch Trubisky or rookie Kenny Pickett at the helm, and the Browns could be looking at an extended stretch with Jacoby Brissett at quarterback.

Aaron Wilson of Pro Football Network reported the league could be looking to suspend Deshaun Watson for the season, and the Browns would turn to Brissett rather than try to reconnect with Baker Mayfield if that were to happen.

5. Dallas Cowboys

It would be hard to consider the Cowboys a big winner this offseason. They traded Amari Cooper for next to nothing, lost out on Randy Gregory in free agency and lost other important pieces in Connor Williams and Cedrick Wilson Jr.

The good news for the Cowboys is they didn't need to win the offseason to have a good chance at repeating as champions in the division.

The division isn't quite as bad as it was in 2020 when the Washington Commanders won with a losing record, but it isn't exactly stacked either.

The biggest addition for the Commanders was Carson Wentz. Given his Week 18 collapse against the Jacksonville Jaguars, that isn't going to strike fear in the hearts of the division.

The Giants still have work to do. They'll be deciding whether Daniel Jones is the quarterback of the future. Brian Daboll should offer a coaching upgrade, but it's hard to predict a one-year turnaround from five consecutive losing seasons.

That leaves the Eagles as the primary competition for the division title. Philadelphia has a good case as the most improved team of the group of four. Adding A.J. Brown, Haason Reddick and Jordan Davis gives them a serious weapon for Jalen Hurts and defensive upgrades.

Whether the Cowboys repeat as champions might depend on Hurts' development as a passer and Dallas' ability to replace the production it lost this offseason.

4. Los Angeles Rams

The Los Angeles Rams will be focused on defending their Super Bowl title, but repeating as NFC West champions is going to be a tall task in its own right.

The NFC West as a division has gotten weaker on paper.

Russell Wilson's departure leaves the Seattle Seahawks in rebuilding mode. The Arizona Cardinals' late-season struggles, DeAndre Hopkins' six-game suspension and the departure of Chandler Jones leave legitimate questions as to how far the Kyler Murray-Kliff Kingsbury tandem can take them.

That leaves the Rams in a two-way race with the San Francisco 49ers.

The Niners finished 10-7 last season but went 2-1 against the Rams head-to-head. Of course, they lost the most important one in the playoffs, but the point remains the 49ers are a legitimate threat.

In terms of major losses, the Rams are going to have to replace the production of Von Miller. The Niners' biggest losses were Alex Mack and Laken Tomlinson. Patching up the interior of the offensive line should be easier than finding a prolific edge-rusher like Miller.

Either way, it's shaping up to be a competitive race between the two for divisional supremacy. That gives the Rams a little tougher path than the teams ahead of them in these rankings.

3. Buffalo Bills

After years of New England Patriots dominance in the AFC East, the division seems to have shifted right into another dynasty.

The Bills snapped an 11-year streak of Patriots AFC East championships in 2020. They took a step back in terms of record in 2021 (going from 13-3 to 11-6) but still wound up clinching the division championship.

Josh Allen's Bills still have a ways to go to establish that kind of dominance over the division, but they are the prohibitive favorite to win the division again.

The BIlls came in No. 2 in Bleacher Report's post-draft power rankings. After taking the Chiefs to the wire in the playoffs, they added an elite edge-rusher in Von Miller.

The only reason the Bills aren't higher is the competition within the division is better than the top two teams on the list.

The Patriots were only one game behind the Bills last season with a rookie Mac Jones. If he shows improvement in his second season, it stands to reason the Patriots could be a threat.

The Dolphins were one of the most improved teams in the league. The defense was solid last season, and they remodeled the offense with the additions of Tyreek Hill, Terron Armstead, Cedrick Wilson Jr. and Connor Williams.

Even the Jets took big steps toward becoming competitive. They had a great draft that included three first-rounders, including Ahmad "Sauce" Gardner, Garrett Wilson and Jermaine Johnson II.

Still, the Bills are in a much better position than the rest to win the division and contend for a Super Bowl.

2. Tampa Bay Buccaneers

Jameis Winston. Sam Darnold. Marcus Mariota.

Those are presumably the three quarterbacks in the way of Tom Brady leading the Bucs to a division title in 2022.

The Bucs are simply at a different stage than the rest of the division. With the retirement of Sean Payton and the loss of Terron Armstead and Marcus Williams for the Saints, there's a level of uncertainty the Bucs don't have.

The Panthers and Falcons are still clearly in a rebuild. Both have rookie quarterbacks in Matt Corral and Desmond Ridder who could supplant their veteran counterparts, but neither is going to threaten the Buccaneers.

Tampa does have questions to answer. Bruce Arians' leadership could be missed as they transition to Todd Bowles as the head coach. But the rest of the cast remains. Retaining Byron Leftwich as offensive coordinator and Brady at quarterback was huge for their continuity.

Jordan Whitehead and Jason Pierre-Paul are the only major losses on the defense. The offense will undergo some changes at both guard spots, but there are few weaknesses on the roster from top to bottom.

After snapping the Saints' four-year win streak in the division, the Bucs are the prohibitive favorites to win back-to-back NFC South titles.

1. Green Bay Packers

There's no division where the disparity between the top team and the rest of the group is larger than the NFC North.

The Packers had the widest margin of victory in their division last season. Their 13-4 record was five games better than the second-place Vikings. It continued a streak of remarkable consistency. The team has won 13 regular-season games in three straight seasons.

There are some questions surrounding the Packers. Davante Adams and Marquez Valdes-Scantling are playing elsewhere and leave behind a combined 224 targets, and they don't have clear answers as to who will carry the torch at receiver and tight end.

The Vikings should once again be the biggest threat to the Packers. They have one of the best groups of running backs and wide receivers with a new coach in Kevin O'Connell, who could help them take the next step.

But it doesn't feel like they are quite good enough to close a five-game gap between themselves and the champions.

The Lions have done some good things and the roster is in better shape than it was last season. That's not enough to challenge for the division just yet.

The Bears are still undergoing a major rebuild. Parting ways with Khalil Mack and Allen Robinson II aren't the kind of moves that will make them a threat to the Packers this season.