There's always an obstacle in the NFL. On the field, it's often a massive defensive lineman who really enjoys giving running backs a close-up view of the finely manicured playing surface. But the internal demons can be worse.

Teams that are clawing for the playoffs or postseason seeding fight those inner obstacles all season. There's a weekly, daily and endless effort to improve and turn weaknesses into strengths. Or, at worst, make sure playoff hopes aren't crushed when fragile areas of a team are exposed.

Every potentially playoff-bound team has at least one such weakness it's working to mask right now as the intensity of late-season games increases. The Kansas City Chiefs, for example, had a dominant defense not long ago, and now suddenly their championship aspirations are at risk as that unit has declined.

The obstacle to clear can take the form of one critical player too, like the Jacksonville Jaguars with Blake Bortles and his baffling decisions that lead to interceptions. Or the Pittsburgh Steelers with Ben Roethlisberger, their quarterback who might be entering his decline phase.

Some obstacles are larger than others, but what usually separates the real title contenders is how well those weaknesses are hidden.

Here's a look at the obstacle each team in the playoff hunt is facing.

Pittsburgh Steelers: Ben Roethlisberger's Struggles

The Pittsburgh Steelers haven't had a losing season since 2003. During that 14-year span, they've won their division six times, finished with 11-plus wins seven times and been to three Super Bowls, winning twice.

But now the end of an era could be coming, at least partially. That streak of sustained success began with the rise of quarterback Ben Roethlisberger, and now at the age of 35, the veteran has openly discussed retirement, possibly in the near future.

This year he's often played like a once-prominent quarterback on the last leg of his career. Roethlisberger's passer rating has been knocked down to another tier compared to 2016, going from 95.4 to 87.8. His per-game passing yardage has taken a similar hit, tumbling from 272.8 yards to 259.7. And his 10 interceptions, five of which came in one game, tie him for third in the league.

Because of his decline, the Steelers offense has had to be one-dimensional while clawing for wins. They've leaned too heavily on running back Le'Veon Bell, who has already taken the punishment of 281 touches over only 10 games.

Holding onto the top spot in the AFC and home-field advantage will likely require a more balanced offense. That means an aging, perhaps fading quarterback needs to rise and play at a Pro Bowl level again. The four touchdown passes Roethlisberger threw during a Thursday night thumping of the Titans was a bounding step in the right direction.

New England Patriots: Still Searching for a Pass Rush

There was a time not too long ago when the New England Patriots defense looked like the largest hurdle they had to overcome in 2017. Now we can look back and laugh about the good ol' days in September when they seemed lost on that side of the ball.

New England was walloped defensively over the first four weeks of the 2017 season, giving up an average of 32.0 points per game. In the five games since then, they haven't even allowed 20-plus points, dropping that weekly average to a mere 13.4 points.

But their one obstacle may still be a specific part of that defense. The part that should be harassing opposing quarterbacks.

After nine games, Patriots pass-rushers have recorded just 16 sacks, which ranks the unit a lowly 26th, and not far from rock bottom. The defenses with the fewest sacks (the New York Giants and Oakland Raiders) are stuck at 13 apiece.

The Patriots risk leaving their secondary exposed while the pass rush struggles to generate anything resembling consistent pressure. 

Kansas City Chiefs: A Defense That Suddenly Lacks Bite

The Kansas City Chiefs won the AFC West in 2016 primarily because of their defense.

Sure, they would give up their share of yards, ranking 24th in that category. But they made those yards irrelevant by clamping down in the red zone and allowing only 19.4 points per game (seventh) and creating a league-leading 33 takeaways.

Now the absence of safety Eric Berry, who suffered a season-ending Achilles injury in Week 1, is really stinging, and consequently the Chiefs will have to win in a different way: by overcoming their feeble defense.

The Chiefs have lost three of their last four games, and they've done it while allowing 24.3 points per game during that stretch. That recent turn southward has brought Kansas City's title contender status into question.

But even during a five-game winning streak to begin the season, there were still concerns. The Chiefs have played nine games, and their defense has allowed 20-plus points in six of them.

They still have a comfortable two-game lead over the Raiders in their division and a soft remaining schedule. So the Chiefs should have little problem holding on to a playoff spot. But playing far beyond that could be difficult with such a leaky defense.

Tennessee Titans: Getting More from Marcus Mariota

Prior to Thursday night the Tennessee Titans were the only division leader in the NFL with a negative point differential.

It sits at a lowly -31 now, which is a measuring stick to show how thin the Titans' margin for error is as they battle the Jacksonville Jaguars for the AFC South crown. Sure, they may have won four straight games before Week 11, but the Titans did that against weak opponents like the Indianapolis Colts and Cleveland Browns. And their average margin of victory in those games was only six points.

They need to flex their offensive muscle a little more to be taken seriously as a playoff contender. Specifically, they need more consistent play from quarterback Marcus Mariota.

The 24-year-old has thrown only eight touchdown passes in his nine starts, and has seen his passer rating fall from 95.6 in 2016 to 79.9 in 2017. He's contributed with his legs, recording 186 rushing yards and four touchdowns on the ground. But he leads a 21st-ranked passing offense that's averaging only 209.9 yards per game and 6.9 per attempt. And he struggled mightily with his ball placement and decision making while throwing four interceptions during a loss to the Steelers Thursday.

Mariota was drafted with the second-overall pick in 2015 to be a dual-threat quarterback who can push his team to critical late-season wins on his own. He's shown that ability in the past when healthy, and now is the time to do it again.

Jacksonville Jaguars: Blake Bortles Can Still Break Your Heart

You don't have to look far for a stunning perspective that shows just how awful the Jacksonville Jaguars have been since their last playoff appearance in 2007.

In fact, you just need to look at their current record. At 6-3, the Jaguars are tied with the Titans atop the AFC South and are behind only because of their head-to-head record. Jacksonville also holds the first wild-card spot in the conference. And it has arrived at that promising perch with six wins, which is already a higher single-season total than any of the Jaguars' past six seasons.

They've done that with a top-ranked scoring defense led by defensive end Calais Campbell, who has been nearly unblockable with 11 sacks overall and three multi-sack games. On the back end, a surging defense is led by A.J. Bouye and Jalen Ramsey, a ball-hawking young cornerback duo who have combined for five interceptions.

But the concern for the Jaguars will always be on the other side of the ball, where quarterback Blake Bortles looms.

The Jaguars have tried to minimize Bortles by leaning on their defense and a rushing offense averaging a league-best 163.0 yards per game. The problem, however, is when the Jaguars get behind and have to hope Bortles doesn't implode.

That almost ended badly in Week 10. The Jaguars defense did its part while giving up only 17 points, but Bortles threw two fourth-quarter interceptions. He did his best to toss the game away, but thankfully the Jaguars were playing the Los Angeles Chargers, who make punting wins an art form.

The Jaguars were still able to force overtime and eventually win their third straight game. But they were reminded that success can be a fragile thing when your starting quarterback has thrown 58 interceptions over 55 regular-season games.

Buffalo Bills: A Run Defense That's Suddenly Getting Pummeled

The Buffalo Bills are still holding on to a playoff spot, but only by a fingernail.

It's getting harder to take them seriously as a playoff contender after they lost two straight games by a combined score of 81-31, with 14 of their own points coming in garbage time during a loss to the New York Jets.

The scoreboard during those games was bad enough, but one specific area of the box score has been the Bills' real undoing. Over just two weeks, they've allowed 492 rushing yards, which is simply unfathomable. Yes, they were napalmed by the New Orleans Saints' running backs for 298 of those yards. But the Jets' backfield also scorched the Bills thoroughly by running for 194 yards.

Winning is always agonizingly difficult in the NFL. It gets a whole lot harder when the opponent not only gets a lead but is also then able to hold on to it by chewing up the clock so easily.

Baltimore Ravens: A Dominant Defense Has Been Wasted by Joe Flacco

It'll be painful to look back at the end of the season and see that one of the NFL's best defenses was wasted. But that seems to be the Baltimore Ravens' destiny, mostly because they have a cratering veteran quarterback.

The Ravens have a swarming defense tied for second in the league lead with 18 takeaways. They also have an imposing pass rush led by the ageless Terrell Suggs, who has accounted for 5.5 sacks and could record his seventh career double-digit sack season.

The Ravens defense does struggle against the run and is ranked 28th while giving up 125.9 yards per game. But in fairness, defending the run gets a lot harder when the defense is exhausted after being on the field too much because the offense can't sustain drives.

Which happens largely thanks to the rapidly declining Joe Flacco. The Ravens have moved the chains on only 34 percent of their third downs, which ranks 28th. Drives either don't get started or fizzle fast after brief success, all while Flacco is averaging an atrocious 5.3 yards per pass attempt, which is down dramatically from his averages in 2016 (6.4) and 2015 (6.8).

A lifeless offense is the reason why the Ravens have lost three of their last four games, and in two of their five losses they failed to score even 10 points. To crawl back into more serious playoff contention, they'll have to lean on a 10th-ranked rushing offense and minimize the damage Flacco can do.

Oakland Raiders: Carr Needs to Lift the Offense

The Bills have started to do their annual midseason plunge, and the Ravens have been spiraling for a while. That puts the Oakland Raiders in prime position to pounce and make us all forget about their four-game losing streak in the first half of 2017.

But to do that, we'll need to see a competent and complete offensive effort for a full game, which has been a rare sight from the current version of Raiders football.

During that losing streak, the Raiders averaged only 13.3 points per game, and overall in 2017 they've already scored less than 20 points in five games. But there's hope that those low-scoring days are fading away, and it's coming from quarterback Derek Carr.

Carr had a sluggish start to his 2017 season and topped the 250-passing-yard mark just once over the Raiders' first five games, though some of those struggles could be attributed to his back injury. But now the Carr we saw in 2016 might be returning, as he's thrown for 300-plus yards in three straight games and averaged 10 yards per attempt in a Week 9 win over the Miami Dolphins.

The Raiders have an opportunity as the teams around them start to flame out. They'll need their quarterback to take over and keep injecting life into the offense.

Philadelphia Eagles: Keeping the Offense Rolling Without Jason Peters

It takes a bit of effort to find the Philadelphia Eagles' weakness, and not just because they're the league's best team at 8-1. No, because they're doing more than just winning games and are pummeling opponents. They have the league's second-best point differential and won their last two games by a combined score of 84-33.

But there is still one massive swirling void to overcome: the loss of left tackle Jason Peters.

His season ended after a torn ACL and MCL in Week 7. Even at the age of 35, he was still one of the steadiest blindside protectors in the NFL. Peters had allowed a mere seven pressures in 2017, according to Pro Football Focus, and was a key cog in the Eagles' thriving passing offense.

It's still too early to know exactly how much his absence will sting and possibly slow down a juggernaut offense. But the Eagles seem to have adjusted well so far to life without Peters, as quarterback Carson Wentz has been sacked just four times over the past two games, including only once against a Denver Broncos pass rush led by outside linebacker Von Miller.

Minnesota Vikings: Who Is the Starting Quarterback?

In a 2017 season filled with injury awfulness that crushes your soul almost every week, we finally saw an uplifting story about a player who was broken not long ago. That happened in Week 10 when Minnesota Vikings quarterback Teddy Bridgewater made his tearful return to the Vikings' active roster after suffering a severe knee injury in August 2016.

Inevitably, that's led to the best problem a soaring team can have.The 7-2 Vikings have won five straight games, and now they're faced with a quarterback decision.

In one corner is Case Keenum, the journeyman who is suddenly having the best season of his career at the age of 29. He may have also logged the best game of his career in Week 10. That's when Keenum averaged 10.5 yards per attempt while completing 72.4 percent of his passes and finishing with 304 yards.

But on his way to four touchdown passes that afternoon, Keenum also threw two ugly interceptions. That's when we saw just how short the leash seems to be with him because Bridgewater sprang up from the bench and put his helmet on.

Bridgewater's recovery story might be inspiring, but it's difficult to arrive at realistic expectations for him after such a long layoff. For what it's worth, he was having a solid preseason in 2016 before the injury, averaging 11 yards per throw over 23 attempts.

Vikings head coach Mike Zimmer seems aware that a regression is likely with Keenum. The larger sample size of Keenum's career before 2017 gives us all the evidence we need: just 24 touchdowns and 20 interceptions over 26 appearances, including 24 starts.

That's why earlier in the week, he was noncommittal on a starter even for Week 11. But although he was tempted to give Bridgewater the start, Zimmer eventually decided to go with Keenum, according to a report from Jay Glazer of Fox Sports.

The job still belongs to Keenum for now, but he might be one wayward throw into the wrong hands away from being benched.

New Orleans Saints: Run Defense Might Be the Only Weakness

The New Orleans Saints are a blazing inferno and have been for seven straight games, the last two of which they won by a combined score of 77-20.

Putting laughably high numbers on the scoreboard has never been a problem for the Saints during the Drew Brees era. Stopping other offenses from doing the same, however, was quite the issue as recently as 2016, when the Saints allowed 28.4 points per game (31st).

Now they've given up 14.3 points per game during their seven-game win streak, which is even skewed a bit by two Detroit Lions touchdowns in Week 6 that weren't the defense's responsibility (an interception return and a punt return).

So finding a weakness with the league's hottest team in every way, especially the rushing offense, becomes an exercise in grasping. The only area in need of improvement right now is still the run defense.

The Saints have a decent, middle-of-the-pack unit in that regard, with a defensive front led by lane-plugging tackle Sheldon Rankins. But they're giving up 4.7 yards per carry (29th), and in a losing cause, Bills running back LeSean McCoy finished with 49 yards on only eight carries in Week 10 (6.1 YPC).

Los Angeles Rams: A Run Defense That's Leaky

The NFC is led by some flamethrowing teams, and the Los Angeles Rams are white hot while trouncing opponents by an average of 25.8 points during a four-game winning streak.

Rookie head coach Sean McVay has lit a fuse to the same offense that Jeff Fisher's dark shadow of ineptitude hid in 2016. The Rams have the league's best scoring offense, and it's anchored by surging sophomore quarterback Jared Goff, an MVP candidate at midseason after he couldn't beat out Case Keenum for the starting quarterback job in 2016. He's supported by running back Todd Gurley, who has found his 2015 Offensive Rookie of the Year form by reeling off seven games with 100-plus yards from scrimmage.

Much like the Saints, the Rams are a well-built NFC steamroller on both sides of the ball. Their pass rush is rooted in the interior pressure created by defensive tackle Aaron Donald. They have 28 sacks (tied for fifth) and are allowing an opposing passer rating of only 73.3 (third).

So also much like the Saints, the Rams' weakness isn't a glaring one, but still an area where they're vulnerable. They have a run defense giving up 118 yards per game (24th) and 4.5 per carry (27th).

Carolina Panthers: The Best Version of Cam Newton Needs to Show Up More

The Carolina Panthers have the defense to keep pace with the Saints in the NFC South. The Panthers have allowed only a field goal in three games, and overall they are giving up a league-best 278 yards per game.

Keeping up with the Saints and other NFC powerhouses offensively, however, is another matter. Especially with quarterback Cam Newton's wild inconsistencies.

Newton dazzled on Monday Night Football against a rudderless Miami Dolphins team. It was a performance highlighted by his 69-yard run, and the 28-year-old also threw four touchdown passes.

But it's difficult to know which Newton will show up on any given week.

Prior to Week 10, Newton had thrown only one touchdown pass over his previous three games, two of which still resulted in wins because the Panthers offense didn't need to score many points. Half of Newton's 10 starts in 2017 have ended with a passer rating below 75. He's also thrown 11 interceptions already after finishing with 14 throughout the entire 2016 season.

The Panthers have the tools on their roster to make the playoffs and also be a frightening opponent come January. They just need their former MVP to start playing like an MVP more often.

Seattle Seahawks: A Crippling Injury to Overcome

There are times when the "next man up" approach to injuries comes to a screeching halt and becomes little more than the standard motivational gibberish from a head coach. It becomes meaningless white noise, which is the case now for the Seattle Seahawks after cornerback Richard Sherman suffered a season-ending injury.

Sherman, who ruptured his Achilles in Week 10, is still a physical force able to shut down half the field. He's long been a core Legion of Boom member, and in seven NFL seasons he has allowed a passer rating in coverage of only 53.0, per PFF.

He's simply irreplaceable, and the Seahawks now face a significant downgrade to Jeremy Lane, Justin Coleman and Shaq Griffin, their top three cornerbacks on the depth chart. Of the three, Griffin has the highest talent ceiling and could continue to ascend in a larger role after recording 10 passes defensed already.

The loss of Sherman is a critical blow to the Seahawks' winning formula of violent, swarming defense that makes sure the offense doesn't need to score much. When the offense does need to score, the hope is quarterback Russell Wilson can run around in circles long enough to make something awesome happen. Even after the addition of tackle Duane Brown, he still plays behind a feeble offensive line. And now with Brown possibly missing Monday's game with a sprained ankle, Wilson might be spinning around even more.

The injuries are mounting heavily for a Seahawks team that's had its playoff success rooted in defense and home-field advantage. The former has taken a hit, and catching the Rams in their division to get at least one home game will be a tough challenge too.

Atlanta Falcons: Finding Any Offensive Consistency

The Atlanta Falcons have produced only a dull roar during the transition to new offensive coordinator Steve Sarkisian. The same core elements of an offense that finished among the top five in rushing, passing and points per game in 2016 have limped through 2017.

The Falcons have scored fewer than 20 points in each of their four losses, and patient zero in that offensive drain has been wide receiver Julio Jones.

You know him as an athletically gifted pass-catcher and a generational talent. Sarkisian knows him as a receiver he still can't get going for reasons that remain unclear.

At 28 years old, Jones still has plenty of prime years left, so age or a deterioration of skill isn't the issue here. He's the same receiver who averaged 100-plus yards per game in each of the four seasons prior to 2017. And he's the same four-time Pro Bowler who has the second-most receiving yards since entering the league in 2011, according to Pro Football Reference.

Yet Jones is averaging 79.4 yards per game in his first season under Sarkisian, which is a steep decline by his standards. That needs to change quickly if the Falcons want to make a second-half push.

Detroit Lions: A Secondary That Can Give Up Yards in Chunks

The hurdle for the Detroit Lions to clear if they want to lock down a wild-card spot has been painfully obvious for a while now. It's also been just painful.

The Lions have a tendency to give up passing yards in mass, unrelenting volumes. They're allowing 247.4 passing yards per game, a large number that tells only a partial story.

Playing pushover offenses can prop up any defense, and the Lions have done that recently by feasting on Cleveland Browns rookie quarterback DeShone Kizer and the Packers' Brett Hundley during just his second career start.

The Lions won both of those games by at least 13 points. However, the defense struggled in the three games prior to that when faced with much tougher quarterback matchups. The Lions dropped games against the Steelers, Panthers and Saints while allowing an average of 286 passing yards per game. And on the ground the Saints also roasted them in Week 6, rushing for 193 yards.

Quarterback Matthew Stafford has done his part to keep the Lions in playoff contention, especially while averaging nine-plus yards per attempt in each of Detroit's past three games. But the defense, and particularly the secondary, threatens to undo those efforts.

On the Outside Looking in

And here are a few more teams still clinging to postseason hopes.

Miami Dolphins: The wild-card standings say the Dolphins are still in playoff contention, so we have to comply and treat them accordingly while doing it with a straight face. But it doesn't feel that way with Jay Cutler, who has been wildly inaccurate while averaging just 5.9 yards per pass attempt.

New York Jets: The Jets have done an awful job at trying to be awful. The assumption was they would be tanking after jettisoning pretty much every veteran on the roster worth anything. Then they won three straight games at one point, and four overall. But their surprising season has been derailed by a poor offensive line that's given up 32 sacks.  

Dallas Cowboys: The Cowboys will be playing without running back Ezekiel Elliott for five more games and could also be missing linebacker Sean Lee for the next three games, according to Brandon George of the Dallas Morning News. That means the core of the Cowboys offense and defense will be gone for a critical stretch in the playoff push, and those depth-chart holes could be too difficult to overcome.

Green Bay Packers: Speaking of injury-induced black holes on a roster, the Packers are showing us just how much their team identity is tied to quarterback Aaron Rodgers, which surprises no one. Hopping over four teams to make the playoffs and doing it with Brett Hundley at quarterback feels daunting, though maybe slightly less impossible after his 8.5 yards per attempt and 110.7 passer rating in Week 10.