Playoff contenders aren't always easy to see coming. 

While the New England Patriots of the sporting world aren't hard to figure out, the NFL loves to stress the "P" word—parity—and rightfully so. Unexpected teams often slip into the postseason on the backs of solid roster building and winning the health lottery. 

A year ago, the Chicago Bears served as a good example, recovering from a five-win campaign to earn 12 victories and a trip to the playoffs after a seven-year drought. 

Fast forward to 2019. The following teams have been out of the postseason for a year or more, yet thanks to smart changes, continued development of key players and other factors, they could end up fighting for playoff spots by the time winter arrives.

Green Bay Packers

The Green Bay Packers have been unremarkable over the past two seasons, winning no more than seven games despite the presence of Aaron Rodgers under center. 

The front office punched the reset button this offseason, though, bringing in Matt LaFleur as the new head coach after firing Mike McCarthy in December. Sometimes with a player like Rodgers, all it takes is an infusion of new ideas, and things can get back on track. 

But a revamped defense doesn't hurt. The Packers went big by nabbing safety Adrian Amos from Chicago in free agency and then shoving aside underperforming pass-rushers like Clay Matthews and Nick Perry for Preston Smith and Za'Darius Smith. Rashan Gary, the No. 12 overall pick in April's draft, only improves things up front for that unit, and third-round rookie tight end Jace Sternberger could help space the offense. 

That doesn't account for returning talent, of course. Better coaching might unlock Jimmy Graham, who only scored twice last year. Wide receiver Davante Adams is still the top weapon. The secondary already boasted huge upside before the addition of Amos. 

Last season, the Packers lost five games by seven points or fewer, including a contest against a Super Bowl participant (the Los Angeles Rams) and two against NFC North rivals. With a new coach and a rejuvenated defense, the Packers should be back in the playoff conversation in 2019. 

Buffalo Bills

Consider the Buffalo Bills back in the playoff hunt for the long run. 

The franchise had a strange playoff appearance in 2017 courtesy of some help from other teams, but it was an anomaly more than anything: It was the first time the Bills had made a postseason appearance since 1999. 

But playoff appearances should be more consistent now. Josh Allen was at least encouraging as a rookie, throwing for 2,000-plus yards and 10 touchdowns over 12 games (11 starts) and leading the team in rushing with 681 yards and eight more scores. 

More importantly, Buffalo made strides to improve the supporting cast around Allen, who threw 12 interceptions in his debut campaign. 

The arrival of wideout Cole Beasley in free agency should work wonders for the passing game thanks to his reliability. Center Mitch Morse and offensive tackle Ty Nsekhe will help to revive the offensive line (41 sacks allowed in 2018). Second-round pick Cody Ford should have a huge boost to the O-line too. Ed Oliver's selection at No. 9 in April boosts a defense that allowed 23.4 points per game last year. 

These Bills started last season with a 47-3 road loss to the Baltimore Ravens but closed as winners in two of their last three. They split the games with two AFC East rivals, and those same teams (New York Jets and Miami Dolphins) aren't massively trending up. 

Buffalo's impressive offseason combined with Allen's likely natural progression should intersect nicely to produce a postseason contender again. 

San Francisco 49ers

It wouldn't have been unreasonable to see the San Francisco 49ers pop up on lists like this a year ago after the arrival of Jimmy Garoppolo and his encouraging developments under center. 

But Garoppolo tore his ACL in Week 3, throwing Nick Mullens and C.J. Beathard into the fire en route to a four-win campaign. 

So the journey to the playoffs begins again for a franchise that hasn't been there since 2013. Garoppolo is back, and so is 2018 free-agent win Jerick McKinnon, who tore his ACL in practice last September. He'll pair with Matt Breida and Tevin Coleman to form what could be one of the NFL's more explosive backfields.

When Garoppolo isn't riding that running game, he has a top-10 tight end in George Kittle and an intriguing case of field-stretching weapons, including top-40 pick Deebo Samuel. 

None of this has mentioned the defense, which receives a big boost from second overall pick Nick Bosa. The Ohio State product will be getting after quarterbacks alongside running mate Dee Ford, who came over in a trade with the Kansas City Chiefs, and free-agent add Kwon Alexander, who will serve as the Reuben Foster replacement in the middle. 

It is hard to imagine a scenario in which 49ers head coach Kyle Shanahan doesn't make the most of his envisioned offense, which he's structured the roster around. And the addition of surefire pressure creators should forge a complementary defense potent enough to push the team back to contention. 

Oakland Raiders

The Oakland Raiders tanked hard in 2018, throwing away two top-flight players (edge-rusher Khalil Mack, wide receiver Amari Cooper) in return for salary-cap space and some future-minded assets. 

But the way head coach Jon Gruden and the Raiders put those assets to work seems to have accelerated the team's status from a long-term rebuilder to something more closely resembling a playoff contender. 

And it doesn't feel like last time either: The Raiders hit the playoffs in 2016, but it was a blip. The last appearance before that had come in 2002. 

But it's easy to forget Derek Carr topped 4,000 yards last year while getting whipped (51 sacks) behind a bad offensive line and with a tank-worthy roster. Not only is free-agent addition Trent Brown in to upgrade right tackle, but Antonio Brown is also one of the game's top targets. Tyrell Williams is a massive upgrade at receiver too. First-round pick Josh Jacobs has the look of an every-down back who can have a seamless transition. 

Carr's defense didn't miss out on the fun. Lamarcus Joyner joined the secondary and will provide a boost to last year's 19th-ranked passing defense, while first-round picks Clelin Ferrell and Johnathan Abram should make an instant impact to the defensive line and secondary, respectively. 

Granted, the AFC West isn't an easy beast to overcome. But if Carr's offense is humming, it should put up enough points to stay in the race throughout the season. 

Cleveland Browns

The Cleveland Browns cobbled together some serious momentum last year after a Week 11 bye, winning four of their last six games. 

Then the offseason hit, and the arrival of star wideout Odell Beckham Jr. sent shockwaves throughout the NFL. 

But these are the Browns. The franchise hasn't made the playoffs since 2002, so consider it understandable if fans outside of the greater Ohio area aren't all-in. 

But they should be.

Baker Mayfield was the catalyst for it all after the coaching change from Hue Jackson to interim skipper Gregg Williams, and he stormed to a record-setting 27 touchdowns for a rookie and 14 interceptions. Provided the offensive line meets expectations, there should be a Year 2 leap under head coach Freddie Kitchens. Cleveland now knows what worked, and Beckham is joining Jarvis Landry on an offense oozing upside.

Perhaps just as important are the moves made on the other side of the ball. Sheldon Richardson should boost a pass rush that already has Pro Bowler Myles Garrett. Morgan Burnett and top-50 pick Greedy Williams add more to a solid secondary, and two linebackers taken in the top 155 (Sione Takitaki and Mack Williams) bolster the depth.  

Cleveland already felt like a team heading in the right direction provided the right players kept trending upward. The offseason additions should have the Browns right in the thick of things in what could be a crowded AFC North.