The Tennessee Titans are 8-4. On the surface, that’s an ascendant team set to build on last year’s nine-win campaign and end an eight-year playoff drought.

But once you look past the standings, you see a flawed team that strikes fear in no opponent.

The Titans have rebounded from a 2-3 start to run to the top of the AFC South, but confidence-building wins over the Jaguars and Seahawks have been lost in the wake of struggles against the league’s lesser teams. Tennessee has been rocked by the Texans during their four-weeks-of-optimism phase and barely escaped against bottom feeders like the Browns and Colts. A disappointing secondary has turned showdowns against teams with above-average passers into shootouts. A weak aerial game has ensured a lack of ammunition when the Titans need it most.

As a result, the team sits four games over .500 but has a scoring margin of -16. That’s the differential of a 5-7 team, not one gearing up for a playoff run. The Jaguars, for example, are also 8-4 but have outscored opponents by 121 points. So how did Tennessee become the NFL’s least convincing 8-4 team?

Marcus Mariota’s sophomore slump came a year later than expected.

Mariota looked like a franchise building block when he overcame a slow start to 2016 and pushed his Titans into playoff contention. While a probable Pro Bowl bid was stolen away thanks to a broken leg that ended his season a week early, the former No. 2 overall pick was a top-10 quarterback in terms of passing touchdowns, QB rating, and yards per pass.

He hasn’t been able to follow up on that performance. Mariota has struggled to find the end zone in his third year as his touchdown rate has fallen from 5.9 percent to 2.9 percent.

At the same time, he’s throwing more interceptions — his 12 picks in 10 games were already a career high going into Sunday’s win over Houston. As a result, his adjusted yards per pass — an advanced statistic per Pro Football Reference that takes big plays like touchdowns and interceptions into account — has dropped from 7.9 to 6.3. That’s the difference between being the league’s sixth-most efficient quarterback to one who can’t crack the top 20.

He hasn’t gotten much help from an underwhelming receiving corps. Tennessee invested heavily in the offseason to upgrade its pass catchers, but those moves have yet to pay dividends. Fifth-overall pick Corey Davis has just 22 receptions in seven games this fall. Third-round pick Taywan Taylor has been on the field even less. Jets castoff Eric Decker is averaging fewer than 30 receiving yards per game.

Mariota has made Delanie Walker his favorite target. That’s paid dividends between the 20s but failed to translate in the red zone, where defenses sell out hard on the tight end. Walker has only two touchdown receptions this season, each coming in the team’s last two games. That’s forced the third-year passer to turn to less reliable options near the end zone, which has had a definite effect on his scoring margins; Mariota only has 10 touchdown passes through 11 games in 2017.

The running game isn’t as good as it was last year.

A big part of Tennessee’s 2016 turnaround was a space-clearing offensive line anchored by stalwarts like Jack Conklin (a first-team All-Pro) and Taylor Lewan. That group kept Mariota upright, but more importantly, it also cleared space for DeMarco Murray and Derrick Henry to excel. The Titans boasted the league’s third-best rushing offense last season, and those efficient performances created space for Mariota to find targets downfield.

They haven’t been as effective in 2017. Mariota has gone from taking sacks on 5.3 percent of his dropbacks to 6.7 percent. The team’s yards per carry average has dropped from 4.6 to 4.2. Football Outsiders graded that unit as the league’s fifth-best run blocking unit last fall; this year, the Titans line comes in 11th.

It’s difficult to see a clear-cut reason for this step back. The team’s 2016 line has been intact throughout the 2017 season, with only left guard Quinton Spain missing any extended time (two games). The Titans have also been quick to rely on two-tight-end sets with Delanie Walker (71 percent of his team’s snaps) and Jonnu Smith (54 percent) throughout the year, which should provide the extra beef needed to keep defenders at bay. It’s possible this is a lapse or maybe just a regression to the mean.

Either way, it hasn’t been a fatal flaw. While 2017’s blocking has shown signs of decline, it’s still pretty good. The Texans saw that firsthand on Sunday when Murray and Henry ran all over them. The duo needed only 22 carries to chalk up 175 yards between them. It was a solid rebound from Murray, who had averaged just 3.5 yards per carry while ceding ground to Henry, who is ascending in his second year as a pro.

The defense is cause for alarm.

Tennessee beefed up an undermanned defense by adding a score of expensive free agents in 2017, including Logan Ryan, Jonathan Cyprien, Sylvester Williams, and Karl Klug. Those efforts haven’t paid off.

Despite facing a lineup of opposing quarterbacks that’s featured DeShone Kizer, Blake Bortles, Jay Cutler, 2017 Joe Flacco, and Jacoby Brissett, the Titans have allowed opposing passers to post an 88.2 rating against them — good for 17th in a 32-team league. What’s worse — that’s only 0.1 points better than the team had allowed in 2016.

Good quarterbacks have outworked the Tennessee defense. Ben Roethlisberger threw for 299 yards and four touchdowns in a 40-17 Week 11 blowout. Derek Carr threw for 262 yards and two touchdowns in an opening week victory. Deshaun Watson truly and utterly devastated the Titans with five total touchdowns in a 57-14 rout.

While the team’s rushing defense has been solid — Tennessee has allowed only 3.6 yards per carry in 2017 — that inability to stop the pass is a major concern. The club has played three games against teams in the AFC playoff race this season. It’s gone 2-1 in those contests, with the only wins coming against Joe Flacco and Blake Bortles. Flacco, for what it’s worth, currently has a 9:11 touchdown-to-interception ratio. His closest 2017 comparison, from a statistical standpoint, is Brian Hoyer.

That’s bad news in the AFC, where the playoffs run through New England and Pittsburgh. Roethlisberger has already ruined the Titans. Tom Brady would be antsy to do the same.

How do the Titans fix this?

Tennessee is in great position for an AFC South crown or, barring that, a rare playoff berth. Upcoming road games at the Cardinals and 49ers will provide the opportunity to get to 10 wins before returning to Nashville for showdowns with the Rams and the Jaguars. That Week 17 matchup will likely decide a division champion — and determine whether or not the Titans will be able to open the postseason in Nashville, where the team is 5-1.

But if 2017 has taught us anything, it’s that the 2-10 Niners and 5-6 Cardinals can still pose a major threat to a Tennessee team that has struggled to definitively put away underdogs. The Titans have the personnel in the secondary and along the offensive line to make improvements on the fly. The question is whether or not Mike Mularkey can make the changes to unlock the potential that made the team a popular preseason pick.

A renewed effort up front would help this defense considerably. The Titans rank just 24th in the league in sack percentage this fall. Derrick Morgan has followed up on his breakout 2016 with 7.5 sacks this season, but his ability alone hasn’t been a difference maker; the team is 4-3 in games where he records a sack. He needs help collapsing pockets and taking the pressure off an overtaxed secondary.

A bounce-back from the offensive line would do wonders as well, especially given the underwhelming returns from a disappointing receiving corps and the threat of Jacksonville and its league-leading pass rush looming. A powerful 1-2 punch at tailback is enough to buy this team some big wins over lesser teams — Sunday’s victory was a prime example. The Titans will need more than that to claim the AFC South crown or advance beyond the Wild Card round this winter.

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