3 teams crashing down to Earth after promising starts

It's not how you start, but how you finish.

Now more than halfway through the 2015 campaign, the NFL playoff picture is becoming more clear with every passing week.

While some teams are establishing themselves as legitimate contenders, others who made some early noise are beginning to demonstrate just how difficult it can be to sustain success over the course of a grueling 16-game schedule.

Here are three teams that have come crashing down after some early flashes kept them in their respective playoff hunts longer than expected.

Atlanta Falcons

A 5-0 start had the Dan Quinn era off to the best start imaginable. The Falcons were in complete control of their playoff destiny, seemingly having improved by leaps and bounds on both sides of the ball.

Five games later, Atlanta added just one win to its overall record. While the club remains in possession of a wild-card seed at 6-4, it only appears to be a matter of time before that spot is surrendered to one of the several teams quickly gaining ground.

It's tough to pinpoint where things started to go wrong for what appeared to be an upstart Falcons team, but it goes without saying that the offense hit a wall.

The running game has lacked the consistency that gave the unit a reliable means of moving the chains early in the year, and Matt Ryan's mediocre play is doing nothing to make up for the apparent drop off.

Atlanta was really never expected to contend for a playoff spot heading into the year, as there's still plenty of work to be done in the rebuild process, but failing to do so after such an impressive start would make this season all the more disappointing.

New York Jets

Still yet to have answered their long-standing questions at the quarterback position, it was a virtual certainty the Jets' offense was going to regress after a fairly productive start.

What couldn't have been predicted so easily, however, was the manner in which the supposedly dominant defense would also begin to experience some struggles of its own.

A once vaunted Jets defense is now allowing its opponents to move the ball with consistency both on the ground and through the air, putting more pressure on an offense clearly not equipped to carry the load.

The Jets, like Atlanta, remain in playoff contention, but locking up a wild-card spot will be far more challenging than the current standings would suggest.

Darrelle Revis and Antonio Cromartie aren't getting any younger, and if the Jets' defense can't hold opponents off the scoreboard at a better rate, perhaps a quarterback change is in order to capitalize on the more promising upside.

And yes, that means Geno Smith.

Oakland Raiders

The Raiders were one of the most intriguing teams to follow over the first half of the season, as an offense filled with young playmakers had the team in prime position to reach the playoffs for the first time since 2002.

Just two weeks later, after consecutive ugly losses, the Raiders are headed in the wrong direction all too quickly. The offense has finally stalled, managing only 27 points over that span.

The defense, now that the offense is struggling to put opponents on their heels, is regularly being exposed as the thin unit many believed it to be heading into the season.

Oakland certainly has some cornerstone pieces in place, and another productive offseason could very well be enough to address the otherwise thin areas of the roster, but it's become abundantly clear that this team is not ready to compete.

Another loss may be all that's needed to end the Raiders' playoff hopes, and that could even come next week against the Tennessee Titans if they put forth an effort anything similar to that of Sunday's loss to the Detroit Lions.