The NFL prides itself on its parity. It doesn't take long for teams to engineer remarkable turnarounds so long as they hit on their draft picks and make smart upgrades in free agency. It doesn't much for teams to suffer staggering stumbles down the standings -- one or two bad drafts combined with natural regression in a few areas is more than enough to inflict significant damage. 

The 2019 NFL season saw three of the eight division winners fail to repeat as division champions, with the Bears in the NFC North, the Rams in the NFC West, and the Cowboys in the NFC East getting usurped by the Packers, 49ers, and Eagles in their respective divisions. It's incredibly difficult to find sustained success in the NFL, which is why the New England Patriots' run over the past two decades with Bill Belichick, who has guided the Patriots to 17 AFC East titles in a 20-season span, is a marvel. But the Patriots could be in trouble in 2020 in the aftermath of Tom Brady's decision to depart Boston for Tampa Bay.

As the 2020 NFL season approaches and now that free agency and the draft have come and gone -- only a few notable players remain free agents -- we decided now would be an appropriate time to take a look at the eight reigning division champions and rank them by their level of vulnerability. The team ranked eighth is the team that is the least likely to get usurped by one of the other three teams in their division. The team ranked first is the team that is most likely to get usurped by one of the other three teams in their division.

Before we begin, it's worth noting that as much as these rankings are about the eight teams and their outlooks in 2020, it's as much about their level of competition within their divisions. As an example, you'll find the 49ers listed on the top half of the list even though they were the best team in the NFC a season ago and remain one of the league's most talented teams. The reason? They're stuck in the toughest division in all of football. All it'll take is mild regression combined with one of the three teams taking a step forward for the 49ers to surrender their crown. Ranking the 49ers as high as I did is not me saying the 49ers are the fourth-worst team on this list. It's me saying their road to the NFC West crown is far more treacherous than the Eagles' road to the NFC East crown because the Eagles only have to fend off one team as opposed to three.

On that note, we begin in Kansas City with the defending AFC West and Super Bowl champions.

8. Kansas City Chiefs (AFC West)

Since Andy Reid arrived in Kansas City, the Chiefs have won four division titles in seven seasons. All four have come in the past four seasons. Two came with Alex Smith at quarterback. The other two came with Patrick Mahomes, inarguably the best player in football right now. At this point, it's impossible to take anyone other than the Chiefs to win the AFC West. 

While the Raiders and Broncos both made substantial improvements this offseason, both teams are a long ways off from competing with the Chiefs, who by the way, are 11-1 against the AFC West over the past two seasons. The Raiders still haven't solved their long-term problem at quarterback, even if Marcus Mariota gives them a decent insurance plan in the likely event Derek Carr struggles, once again, to make the leap in 2020. The Broncos are still a huge unknown with Drew Lock at quarterback after he flashed promised during his rookie season, but ultimately hasn't shown enough in only five starts to be deemed a franchise-caliber quarterback. As for the Chargers, their defense should be improved after they added Chris Harris in free agency, but they'll be starting either Tyrod Taylor, a fringe NFL starter, or Justin Herbert, a rookie who exhibited clear flaws during his college career, at quarterback. Neither should be expected to keep pace with Mahomes.

In the end, it comes down to the Chiefs having Mahomes and Reid. It makes placing the Chiefs on this list rather easy. Nobody should expect Kansas City to regress in 2019.

7. Baltimore Ravens (AFC North)

The Ravens were the best team in football a year ago during the regular season, winning 12 straight games after starting 2-2, with Lamar Jackson capturing MVP honors. They weren't at all lucky to win as many games as they did with an offense that ranked first in DVOA and a defense that ranked fourth in DVOA. They outscored their opposition by 249 points over the course of the season. Don't let their disappointing performance in the playoffs fool you: The Ravens had an incredible 2019 season, and after adding Calais Campbell in the trade market and Patrick Queen in the first round of the draft, they're primed to sustain their success in 2020. Even if they do take a step back -- it's extremely difficult to win 14 games two years in a row -- they can still win the division with 10 or 11 wins.

While the Steelers should be improved without Mason Rudolph and Devlin Hodges under center, they're counting on Ben Roethlisberger -- at the age of 38, without an improved offseason workout regimen, and after major elbow surgery -- to elevate them above the Ravens. The Browns are still the Browns, talented, but flawed -- until they demonstrate they're a playoff-caliber team, it's best to avoid picking them to make the playoffs (says the guy who picked them to do exactly that a year ago). As for the Bengals, while their long-term future is bright with Joe Burrow, they were able to pick Burrow first overall for a reason: They're not any good. 

It comes down to how much you think the Ravens will regress after a 14-2 season and how many wins Big Ben is worth. While I think the Ravens will win closer to 10 games than 16 games, I also don't think the Steelers will improve as much as we think just because of Big Ben. Remember, defensive success tends to fluctuate on a year-to-year basis, and the Steelers rode their defense to eight wins. That same defense racked up a league-high 38 takeaways, which also tends to fluctuate on a year-to-year basis. What I'm trying to say is that the Steelers' defense could very well regress in 2020, which means it'll be up to a 38-year-old quarterback coming off major surgery to lead the Steelers past a team that went 14-2 a year ago. I'll take the Ravens, assuming Jackson stays healthy, of course.

Drew Brees (right), Sean Payton and the Saints are still the team to beat in the NFC South.  Getty Images

6. New Orleans Saints (NFC South)

Tom Brady's arrival in Tampa Bay has certainly made the NFC South more competitive than it was a year ago, when the Saints won 13 games and second place belonged to the 7-9 Falcons and 7-9 Buccaneers, but the NFC South is still very much the Saints' division. They're bringing back most of their important contributors, most notably Drew Brees. Their biggest loss was Teddy Bridgewater, their backup quarterback who won all five of his starts filling in for Brees a year ago, but they managed to replace him with Jameis Winston, giving them the best backup quarterback situation in all of football. Over the past three seasons, with so many of the components that compose the Saints' current core, the Saints have gone 37-11.

Assuming the Saints will win anywhere between 11-13 games, as they've done over the past three years, the question then becomes if you think Tom Brady and Rob Gronkowski are worth 4-6 wins. For as good as that duo was together in New England, I'm skeptical. While Brady, who will be 43 when the season begins, didn't have much help a year ago, he graded out as a fairly average quarterback by the advanced metrics (17th in both DVOA, which measures value per play, and total QBR). Meanwhile, Gronk clearly wasn't operating anywhere close to his peak the last time we saw him in 2018. 

I don't want this to come across as an overly negative assessment of the Buccaneers' outlook. I think they're going to win 10 games and make the playoffs. I think their defense remains supremely underrated (fifth in DVOA a year ago). I just think the Saints are the better team. For as well a Brady as aged, Brees is aging even better. At this stage in his career, he's better than Brady. The two defenses are comparable. And unlike the Buccaneers, the Saints won't have to undergo any major transitions on either side of the ball during a truncated offseason. They'll have continuity. For all those reasons, the Saints are well positioned to fend off the Buccaneers in the NFC South.

5. Philadelphia Eagles (NFC East)

The Eagles are not better than the four teams they're ranked above. But they're listed at No. 5 because they only have one team to worry about in the NFC East in the Cowboys while many of the teams listed below have two or three teams hot on their heels. But the Eagles have reason to fear the Cowboys, which is why they're ranked below the the aforementioned three teams.

For one, the Eagles simply weren't that good a year ago, winning only nine games and outscoring their opposition by 31 points. For the sake of comparison, the Cowboys, who went 8-8, outscored their opposition by 113 points. Two, the Cowboys are coming off an offseason that saw them get rid of their biggest weakness in coach Jason Garrett and enjoy one of the best drafts across the entire league. Like the Saints, the Cowboys have a great insurance plan behind their starting quarterback in Andy Dalton. As for the Cowboys' starting quarterback, Dak Prescott, he's still supremely underrated. In 2019, he played at a near-MVP level, ranking sixth in DVOA and fourth in total QBR. With the addition of CeeDee Lamb, who gives Prescott a legitimate third weapon in the passing game alongside Amari Cooper and Michael Gallup, the Cowboys might have one of the best offenses in the entire league in 2020. Three, the Eagles might have a huge problem at left tackle with Jason Peters still unsigned and Andre Dillard far from a sure thing.

But the Eagles are at least well positioned to fight off the Cowboys. Their biggest issue a year ago was their health at receiver. Assuming Alshon Jeffery and DeSean Jackson enjoy better injury luck in 2020, Jalen Reagor contributes as a rookie, and Marquise Goodwin gives Carson Wentz another vertical threat, the Eagles' offense should improve. Defensively, they lost Malcolm Jenkins, but Darius Slay is the shutdown cornerback their defense was lacking a season ago.

The Eagles and Cowboys are neck and neck in the NFC East. I can see it going either way. I think it'll come down to their head-to-head matchups. The division could very well be decided by a tiebreaker.

4. San Francisco 49ers (NFC West)

The 49ers should've won the Super Bowl. To lose to the Chiefs, everything that needed to go wrong did go wrong in the fourth quarter. While that's obviously a massive disappointment to the franchise, it's also a sign of how close the 49ers are to winning a championship. They're only a few bounces away. As of May, before preseason and training camp injuries can wreck a season, the 49ers are either the best or second-best team in the NFC (the Saints might not have the same caliber of defense, but they have the edge at quarterback). So, it might come as a surprise to see them listed fourth here.

This is less about the 49ers and more about the competition they'll face within the NFC West. A year ago, the Seahawks came one lousy yard away from winning the division. They still have Russell Wilson, who is good enough to make up the gap in talent between the Seahawks and the superior 49ers. The Rams are coming off a disappointing season, but so many people seem to forget that the Rams still won nine games a year ago. The idea that they're suddenly bad is misleading. They were a break or two away from making the playoffs. The Cardinals are coming off a 5-10-1 season, but they also have the reigning Offensive Rookie of the Year in quarterback Kyler Murray and they just added DeAndre Hopkins in a trade that wound up being the steal of the offseason -- not to mention they got tremendous value by drafting Isaiah Simmons in the first round. They probably won't go from five wins to dethroning the 49ers in the span of a single season, but they're going to be far more dangerous. The point being, the 49ers are stuck in the league's toughest division. For as good as they were in 2019, they were a yard away from being a wild-card team, which would've made their journey to the Super Bowl far more treacherous.

That said, there are also some internal reasons to suspect the 49ers could be due for some regression. They traded their best player on their defensive front, sending to DeForest Buckner to the Colts in exchange for a first-round pick, which they turned into Buckner's replacement in Javon Kinlaw. While Kinlaw is both younger and cheaper than Buckner and has the potential to become as good as Buckner, he's not as good as Buckner yet. That'll be a tough loss to survive. Similarly, the 49ers drafted Brandon Aiyuk to replace Emmanuel Sanders, but while Aiyuk has loads of potential, it can take some time for young receivers to find their footing in the NFL. 

In short, the 49ers have lost some key pieces. Combine those losses with the competitive state of the division and the 49ers could be a division winner that fails to repeat in 2020. That said, it'd be shocking to see the 49ers completely fall flat on their face. I think they'll be really good again in 2020, just not quite as good as they were in 2019. 

Not to mention, they'll have to deal with the dreaded Super Bowl hangover.

The Packers didn't do much to help Aaron Rodgers this offseason.  USATSI

3. Green Bay Packers (NFC North)

The Packers went 13-3 a year ago and came up a game short of reaching the Super Bowl, but by expected win total, the Packers were really projected to win 9.7 games. They were a good team, just not as good as their 13-3 record indicated. 

The easiest way to offset regression is to improve your roster in free agency and the draft. That's what makes the Packers' offseason so disappointing. They didn't just lose right tackle Bryan Bulaga and linebacker Blake Martinez in free agency. They failed to upgrade their biggest area of need (receiver) even though their biggest area of need also happened to be the deepest position group in the draft (arguably ever). Instead, they drafted a quarterback in the first round to sit behind Aaron Rodgers for at least two seasons, an old-school running back who seldom catches passes in the second round, and an H-back in the third round. The Packers didn't use any of their nine picks on a receiver. It's indefensible. If Love ends up becoming the next Aaron Rodgers or Brett Favre in the long term, nobody will care about the Packers' inability to add reinforcements in the short term, but the chances of a developmental quarterback becoming a franchise quarterback are slim. If we're only looking ahead at the 2020 season, which is the very purpose of this article, it's impossible to defend the Packers' draft.

The good news for the Packers is that the rest of the division didn't capitalize on their failure. While the Vikings did well to add plenty of talent in the draft, those rookies are being asked to replace established veterans like Stefon Diggs, Linval Joseph, and Everson Griffen. It's not reasonable to expect them to fill their voids in 2020. It typically takes time for rookies to acclimate to the NFL. The Bears, meanwhile, added even more weapons to a stacked defense, but by trading for Nick Foles, they didn't bring in a big enough upgrade at quarterback over Mitchell Trubisky. Finally, the Lions are still the Lions -- they're more than one offseason away from seriously challenging for the NFC North title, unless everything happens to break their way.

The Packers are still very much alive in the fight for the NFC North crown. It should be close. But their inability to address the biggest holes on their roster after a 13-3 season that wasn't as good as their win total indicated could cost them in 2020.

2. New England Patriots (AFC East)

If Bill Belichick wasn't still their coach, the Patriots would rank first on this list. But Bill Belichick is still their coach and he has a long history of surviving the loss of his starting quarterback -- whether it's winning the Super Bowl in 2001 with his backup quarterback after Drew Bledsoe went down with an injury or going 11-5 with Matt Cassel when Tom Brady went down with an injury or posting a 3-1 record with Jimmy Garoppolo and Jacoby Brissett during Brady's Deflategate suspension in 2016. If anyone can survive the departure of Brady, it's Belichick.

But if you were to examine the talent levels of all four rosters in the AFC East, you wouldn't say the Patriots have the most talented roster. That honor belongs to the Bills, even if there are legitimate questions about quarterback Josh Allen. Even the Jets, who should benefit from improved injury luck, and the Dolphins, who made massive improvements in free agency and the draft, should be able to compete with the Patriots. It's never been more difficult to make predictions about the AFC East. 

The biggest question in all of this is Jarrett Stidham. By not signing Andy Dalton or Jameis Winston and by declining to draft Jordan Love in the first round and Jalen Hurts in the second round, Belichick has expressed confidence in Stidham, a fourth-round pick a year ago who seldom saw the field in 2019. When he did step in under center, he promptly threw a pick-six to Jamal Adams and the Patriots put Brady right back into the game to close out their win. But Belichick knows more about Stidham's ability than any of us. If he has confidence in Stidham, I have some confidence in him too.

The problem is, even if Stidham ends up being good and Belichick coaches up the defense like he always does, the Patriots could still lose the division to a 10-win Bills team with a nasty defense and an offense full of playmakers now that Stefon Diggs has arrived via trade. It's going to be close. As of May, it's simply too close to call. Without knowing just how good or how bad Stidham is, it's nearly impossible to predict how the AFC East will shake out.

When's the last time we've been able to say that about the AFC East?

1. Houston Texans (AFC South)

Having Deshaun Watson means the Texans have the best quarterback in the AFC South, which gives them an advantage over the Colts, Titans, and Jaguars. But the Texans can't get out of their own damn way. Instead of trying to make Watson's life easier, they're hellbent on making his job as difficult as possible. The latest example is their decision to trade away DeAndre Hopkins -- their best player not named Deshaun Watson -- in an indefensible move. 

In return, the Texans did not get a first-round pick from the Arizona Cardinals. Instead, the Texans settled for 28-year-old running back David Johnson, who hasn't been a star player since 2016 -- when Deshaun Watson was still the quarterback at Clemson -- but is under contract at the price of a star player, plus a 2020 second rounder and a 2021 fourth rounder. The Texans also sent a fourth-round pick to the Cardinals to sweeten the deal, because, well -- the truth is, there simply isn't a justifiable explanation for any aspects of the trade from Houston's perspective.

The truth is, Watson is well used to covering up the Texans' flaws, from their leaky offensive line to their unimpressive defense. Don't expect the Texans to suddenly suck without Hopkins. While Hopkins is one of the best receivers in football, Watson is still one of the best quarterbacks in football. He's capable of dragging this team to the top of the AFC South.

The problem is, while the Texans got worse this offseason, the rest of the division got better -- not including the Jaguars, who are entering the beginning stages of yet another rebuild. The Colts, who won seven games last year without a starting-caliber quarterback, added Philip Rivers. The Titans, who finished the season on a 7-3 tear and journeyed all the way to the AFC Championship Game after making the switch from Marcus Mariota to Ryan Tannehill, managed to bring back most of their core in free agency (with the notable exception of Jack Conklin) before adding Conklin's replacement Isaiah Wilson in the draft and bolstering their secondary by taking Kristian Fulton in the second round. 

Those three team should be in a tight race for the AFC South trophy. While the Texans have the best quarterback of the bunch, assuming Tannehill fails to sustain his ridiculously great level of play from the second half of last season, they have the worst overall roster of the bunch, making them susceptible to both potential usurpers.