Not all 2-0 starts in the NFL are alike.

To be sure, being unbeaten through the first two weeks of the season is cause for any organization to celebrate. Since 1990, teams that have started 2-0 have reached the playoffs 63.9% of the time.

Yet with the scheduling setup and other factors weighing so heavily on such a small sample size, some teams that burst out of the gates are bound to slow down or trip up. While six of the nine teams that reached the 2-0 mark last season made the playoffs, several proved unfit for the long haul.

With that in mind, here's USA TODAY Sports' ranking of this year's nine 2-0 teams based on their contender credentials, with the franchises sorted into three tiers.

Legit contenders

1. Kansas City Chiefs

If not for ending up on the favorable side of a couple fourth-quarter plays, the Chiefs easily could be 0-2 and sparking panic about their Super Bowl three-peat bid. Call it good luck or championship mettle – or some combination of both – but Kansas City once again finds itself 2-0 for the fifth time in seven seasons with Patrick Mahomes as the starting quarterback. Between Marquise "Hollywood" Brown's long-term shoulder injury and rookie left tackle Kingsley Suamataia's benching on Sunday, visions of a far more explosive offense might have been premature. But this remains the team that everyone is chasing, and there's reason to believe that significant improvement is within reach, especially with Travis Kelce barely factoring into the passing attack thus far. With Mahomes still capable of finding a spark at a moment's notice and Steve Spagnuolo's defense continuing to deliver in key spots, Kansas City's margin for error feels as big as ever.

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2. Buffalo Bills

An offseason of roster upheaval has only given way to more personnel hits for Buffalo, which has lost linebackers Matt Milano and Terrel Bernard as well as cornerback Taron Johnson to injuries. But the Bills haven't buckled yet. With Joe Brady establishing himself as one of the NFL's most adaptable offensive minds, Josh Allen and Co. have shown any number of ways to exploit defenses despite still sorting out a reconfigured receiving corps. Sean McDermott will eventually have to demonstrate he can overcome the hits that could prove to be the difference against the AFC's elite. For now, however, the Bills are one of the few teams capable of meeting the Chiefs – or any other top contender – at their best.

3. Houston Texans

Tied with the Chiefs for the lowest point differential (+8) of all the undefeated teams, the Texans didn't exactly mow down their first two opponents. The defense also was able to tee off against Anthony Richardson and Caleb Williams, who have a combined six starts between them. But Houston has the all the necessary talent to be a title threat, and reigning NFL Coach of the Year DeMeco Ryans continues to position his group to succeed. Sustained improvement in the running game could put the team over the top, as Joe Mixon looked rejuvenated in his 159-yard performance in Week 1 but then suffered an ankle injury against the Chicago Bears. With the AFC South looking nowhere near as competitive as it appeared it might be, the Texans could run away with another division title and make a push for very favorable seeding.

Almost there

4. Tampa Bay Buccaneers

Maybe it's time to stop expecting a falling off for the three-time defending NFC South champions, who are enjoying their fourth consecutive 2-0 start. The first two came as a recognized powerhouse with Tom Brady behind center. But Baker Mayfield and Todd Bowles have fended off any notion of a regression, and their 20-16 victory Sunday over the Detroit Lions served as a reminder that Tampa Bay belongs among the conference's best. The resurgence of Chris Godwin is a major boon for the offense, while Bowles' group continues to hold firm when in key spots. A stagnant run game and shortage of firepower in the pass rush remain potential long-term limitations, but the Buccaneers' abilities are readily evident.

5. New Orleans Saints

While the Saints have been pilloried for continuing to double down on a roster that has produced middling results in recent years, the franchise might be responsible for the most consequential move of the offseason. The hiring of offensive coordinator Klint Kubiak activated something in a veteran-laden attack that few could have seen coming, as New Orleans' 91 points are tied for the fourth most in league history through a team's first two games. It must be noted, however, that the scoring outbursts came against the hapless Carolina Panthers and a Dallas Cowboys defense playing in its second game within a new scheme. Still, the rampant use of motion and play-action has done wonders for both Derek Carr, who looks far more confident after a rocky debut season in the Big Easy, and Alvin Kamara, the five-time Pro Bowler who leads the NFL in yards from scrimmage (290) after averaging just 3.9 yards per rush last season. If the Saints can handle a brutal upcoming four-game stretch (vs. Eagles, at Falcons, at Chiefs, vs. Buccaneers), then kick them up a tier. For now, though, put a pin in any projection of a home Super Bowl.

More to prove

6. Minnesota Vikings

It's understandable that the focus of the Vikings' sizzling start has been Sam Darnold, as it's not often that a former top-five pick serves a reminder of his promise upon joining his fourth team (Mayfield, of course, was the pioneer here). But there's little question that more recognition should be given to defensive coordinator Brian Flores. As San Francisco 49ers quarterback Brock Purdy put it to Flores after Minnesota bagged him for six sacks and two turnovers in a 23-17 win on Sunday, "Your scheme is crazy." While Flores should continue to fluster opposing attacks throughout the season, Darnold still must demonstrate that he can be a consistent triggerman and do more than let Justin Jefferson be Justin Jefferson. But if Kevin O'Connell can continue to put him in favorable spots – and the mounting injuries to his pass catchers don't take too much of a toll – Minnesota could be in the wild-card mix late into the season.

7. Los Angeles Chargers

With more yards rushing (395) than passing (270), Jim Harbaugh's crew has already established its NFL counterculture identity. Yet the approach used to grind down the Raiders and Panthers almost certainly won't be deployed as easily against the likes of the Steelers and Chiefs, who await the next two weeks. The Bolts' dominant defensive performances are inextricably tied to the moribund passing attacks they faced, and an underdeveloped receiving corps threatens to be a stumbling block when early-game conditions are less favorable. Still, even if the group can't quite keep up with contenders, the schedule is soft enough that the Chargers could be a rough-and-tumble version of last year's Dolphins, overpowering the league's subpar-to-average teams to stay relevant in the postseason picture.

8. Pittsburgh Steelers

It's fitting that the Steelers are squaring off with the Chargers on Sunday, as the two have plenty of overlapping traits. Like Los Angeles' group, Pittsburgh's defense has smothered its overwhelmed opponents, but the unit is in need of a greater test. And the Steelers haven't had to make much of an ask of their passing game with Justin Fields filling in for Russell Wilson. Still, while Mike Tomlin has proven himself adept at navigating roster deficiencies that would sink lesser coaches, this formula doesn't appear tenable for the long run, as neither Fields nor Wilson look capable of bailing the offense out the way Herbert can. A league-best +5 turnover differential has been key to Pittsburgh's early success. Maybe the defense can continue to generate big plays, but the offense could be facing some bigger holes ahead if the team sticks with Fields, who had 41 turnovers in 40 games with the Chicago Bears while taking 135 sacks in the same span.

9. Seattle Seahawks

Credit Mike Macdonald, the NFL's youngest coach at 37, for getting off on the right foot with an unblemished start – something no other coach in franchise history has managed in his first year. But there was no easier opening slate than the one Seattle had in facing the Denver Broncos and New England Patriots, with each franchise sorting through major roster resets. Macdonald's complex scheme will likely continue to vex opponents throughout the season, and Geno Smith looks fully in command of new offensive coordinator Ryan Grubb's attack. But an offensive line that ranks 31st in both ESPN's pass block win rate (38%) and run block win rate (65%) remains a major liability, particularly on the interior. While the Seahawks might be far more competitive than many predicted, a regression seems inevitable once the level of competition ratchets up.

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