Ryan Tannehill, acquired by the Tennessee Titans from the Miami Dolphins for draft picks last spring, initially was looked at as an insurance policy for starting quarterback Marcus Mariota, a former first-round pick with injury concerns.

“He understands that he’s coming in as a backup quarterback,” Titans GM Jon Robinson said of Tannehill in May.

Instead, Tennessee got a fringe MVP candidate who has put the Titans in the thick of the playoff race.

The 8-5 Titans can’t clinch a playoff spot this week but they are tied with Houston atop the AFC South and favored over the Texans on Sunday at home. A win would improve Tennessee’s postseason chances from 57 to 77 percent, according to the New York Times playoff calculator. If the Titans win Sunday and again when they face the Texans in the regular season finale, Tennessee would lock up the division title and host a wild-card game. Even if they don’t win in the division, they are in the hunt for a wild-card spot, tied with the Pittsburgh Steelers for the final berth, although Pittsburgh owns the tiebreaker.

It’s a far cry from the situation Tennessee faced when Tannehill took over the starting job in Week 7 from a struggling Mariota. The Titans were 2-4, two games back of the Texans and coming off back-to-back losses in which they scored a total of seven points.

“A change at quarterback could be on the horizon, but the problems reach beyond that position,” ESPN.com wrote at the time.

With Tannehill starting, the Titans have gone 6-1 since, averaging 31.4 points, with the 31-year-old quarterback showing why he was a first-round pick out of Texas A&M in 2012. Tannehill was even named the AFC offensive player of the week after the Titans’ 42-21 win over the Oakland Raiders last weekend, his first such honor since 2015. He completed 21 of 27 passes for 391 yards in that contest, throwing three touchdowns and an interception. According to NFL.com analyst Gil Brandt, he’s the only quarterback in NFL history other than Seattle’s Russell Wilson to have a stretch of four games with at least two passing touchdowns and a quarterback rating of 125 or higher.

Tannehill has resisted calls to take stock of his stellar play, saying “I’ve seen how this thing goes. The waves and the ins and outs of the season, so if you start taking a step back at this point, then you’re doing a disservice to your teammates and to yourself.”

Still, it’s hard not to gawk at his numbers. Tannehill leads the NFL in yards per attempt (9.8) and passer rating (118.5). He ranks in the top five in completion rate (73.4 percent), touchdown rate (8.9 percent) and first-down rate (44.3 percent). He has been the seventh-best passer of 2019, according to the game charters at Pro Football Focus — and that includes all quarterbacks’ performances from the beginning of the season.

Looking at production only since Week 7, when Tannehill made his first start, he has been the league’s fourth-best passer, behind only Baltimore’s Lamar Jackson, the MVP front-runner; Wilson, another popular MVP candidate; and New Orleans’s Drew Brees.

He’s been money at crunchtime,” Oakland Coach Jon Gruden said ahead of the Week 14 matchup. “You saw the Chiefs game. He’s played very, very good football when all the chips are on the table. That’s No. 1. And he’s showcasing his dual threat ability. He can throw it, he can run it, and they run a lot of creative plays with him because of his athleticism..”

The biggest improvement the Titans have seen after switching from Mariota to Tannehill is in accuracy. Tannehill leads the league in completion percentage above expectation, meaning he is outperforming expectations when considering three factors: how much separation the intended receiver had from the nearest defender, where the receiver is on the field and the separation the passer had from the nearest pass rusher at the time of throw. That’s no small feat considering Tannehill is not afraid to take chances down the field: He is averaging better than nine air yards per attempt, the fifth-highest mark among passers this season.

In addition, 20 percent of Tannehill’s passes have been thrown into tight coverage, according to the NFL’s Next Gen stats. Only three quarterbacks with at least 200 passing attempts — Matthew Stafford, Daniel Jones and Ryan Fitzpatrick — have thrown more often into tight windows this season, and they’re a combined 8-19-1 as starters.

Mariota, by comparison, completed fewer passes than you would have expected this season (59 percent, compared with 62 percent expected) while averaging just seven air yards per attempt in 2019.

A higher completion rate naturally leads to a more efficient offense. From Weeks 1 to 6, with Mariota as the starter, the Titans scored 1.3 points per drive (30th) and converted 53 percent of their red-zone opportunities (tied for 18th). During Weeks 7 to 14, with Tannehill under center, that has improved to 2.5 points per drive (fifth) and 86 percent in the red zone (first).

There has been a noticeable boost for running back Derrick Henry, too. He produced four rushing touchdowns over 113 carries during the first six weeks of the season while averaging 3.7 yards per carry. Since Week 7, Henry has nine touchdowns on 137 carries while averaging better than six yards per tote. He shares the league lead with 13 rushing touchdowns, taking advantage of defenses as they scramble to stop the Titans’ newly potent passing attack.

“We just have to keep it rolling. The offense is firing on all cylinders right now,” Tennessee’s offensive tackle Jack Conklin said. “That’s the goal for us every week: Come in and wear down a team.”

Read more on the NFL: