NASHVILLE, Tenn. -- A lot of things went right after quarterback Ryan Tannehill took over for Marcus Mariota as the starter in Week 7 of the 2019 season.

Despite a slow start, the Tennessee Titans offense finished with its highest points-per-game average (25.1 PPG) in the past five years.

The challenge in 2020: Can the Titans' offense pick up where it left off?

Offensive coordinator Arthur Smith believes the first step is a stronger start. The Titans scored 16.3 points per game (ranked 28th) in the six games Mariota started last season. In the other 10 under Tannehill, the Titans scored 30.4 PPG (ranked third).

This season, Tannehill will be under center from the beginning. The familiarity that Smith and Tannehill developed last season should bode well for 2020.

"The hardest thing to do in this business is sustain success," Smith said. "Ryan did a good job last year. I feel very confident in Ryan. He and I have a great relationship; I enjoy working with him. We see the game very similarly. It’s fun talking football when we go in there and meet. I’m excited about the leadership Ryan will bring, too."

Added former NFL general manager and current ESPN NFL analyst Mike Tannenbaum: "With the same coordinator and quarterback coming back, it should give them a chance to have continued success. Having Arthur Smith and Ryan Tannehill together for a second year will only serve them well, having continuity at those two key positions."

There are layers to the success the Titans experienced last season. A lot of things fell into place, mostly the performances by Tannehill, running back Derrick Henry and wide receiver A.J. Brown. Tennessee finished with a 7-3 record after Tannehill took over as the starter in a 23-20 victory over the Los Angeles Chargers on Oct. 20.

It will be tough for Tannehill to duplicate a season in which he completed 70.3% of his passes and averaged 9.6 yards per completion. In NFL history, only Hall of Fame quarterbacks Sammy Baugh (Washington, 1945) and Joe Montana (49ers, 1989) were able to finish a season with an average of more than 9 yards per completion and a completion percentage of 70 or better.

There weren't many situations where Tannehill was more dangerous than with play-action passes. He completed 76.5% and had an average of 13.6 yards per attempt on play-action passes last year, with both stats the highest among any quarterbacks with at least 75 play-action pass attempts. His average play-action completion gained 17.8 yards, also best in the NFL.

The success of the Titans' play-action passing game hinges on Henry's effectiveness as a runner. The threat of Henry running the ball forces linebackers or safeties to take false steps, leading to them getting caught out of position to effectively defend pass attempts.

"It is about Derrick Henry. ... It's what [coach Mike] Vrabel wants to do: Run the ball with Henry and play solid defense," said Doug Kezirian, host of ESPN's Daily Wager. "He's only missed one game in the last three years. That was last year, Week 16 ... They didn't really need it, and in Week 17 he came back and had over 30 carries for over 200 yards."

Keeping Henry healthy is critical to Tennessee's offensive success since he takes on such a heavy workload. He carried the ball 303 times during the regular season and still managed to average 5.1 yards per carry. He had an additional 83 carries in the playoffs and averaged 5.4 YPC.

Teams focused on stopping Henry by stacking eight defenders in the box. It didn't matter. According to ESPN Stats & Information, when facing with eight defenders in the box last season, Henry accounted for 572 rushing yards, 12 rushing touchdowns and 235 yards after contact, all of which were league highs.

Will the heavy workload catch up to Henry? There's the cautionary tale of former Kansas City Chiefs running back Larry Johnson, who carried the ball 336 times for 1,750 yards in 2005 and 416 times for 1,789 yards in 2006. But he was never the same after those two seasons, gaining 2,011 yards combined over the next five years.

It's safe to expect some drop-off from his spectacular 2019 season, but his coach is confident Henry can keep it up.

"I think Derrick trains and prepares to be able to handle that load," Vrabel said. "He’s very unique ... He’s durable and he’s one of the best-conditioned players on our team."

Henry wasn't the Titans' only home run threat last season. Brown finished with four touchdown receptions of 50-plus yards last season. That was the most since Randy Moss had five touchdown receptions of 50-plus yards in 1998, according to ESPN Stats & Information.

It's been all Derrick Henry lately for the #Titans. Defenses will focus on that. Here's a way to get A.J. Brown back in the mix as an impact player vs the #Chiefs. pic.twitter.com/aUySweAruk

— TURRON DAVENPORT (@TDavenport_NFL) January 13, 2020

Brown finished with 20.2 yards per reception (second-most behind the Chargers' Mike Williams), including a league-high 8.8 yards after the catch. Expecting a repeat of those gaudy numbers from last season could be asking a lot.

Smith believes the Titans have a lot of guys that can "take it to the house" and vows to showcase them as an explosive unit overall. Smith is working on ways to get more creative and make sure more players get touches because he doesn't want to see a regression in explosive plays.

The Titans offense is taking an approach that is similar to the Golden State Warriors when they won NBA championships from 2016-18 with Stephen Curry, Klay Thompson and Kevin Durant. They had multiple players that were capable of scoring 40 points on any night.

Finding ways to get players like wide receiver Corey Davis, tight end Jonnu Smith and others involved will make the Titans harder to defend. It was one of the keys to their NFL-best 77% red zone touchdown percentage last season.

Both Smith and Davis caught TD passes in the red zone during Tennessee's 28-12 divisional playoff win over the Baltimore Ravens. There really wasn't any particular player to focus on in the passing game when the Titans were inside the red zone.

"We had multiple people score touchdowns which kind of [helped] to spread it out," Arthur Smith said.

With all of the weapons at Smith's disposal, it's important to find ways to extend drives. That's where improving on third-down efficiency comes into play. They'll look to Adam Humphries to be the third-down specialist they hoped for when they signed him to a four-year deal worth $36 million before last season, when he missed the final four games.

Tennessee is returning 10 of their 11 offensive starters from last season. Offensive tackle Jack Conklin signed a free-agent deal with the Cleveland Browns, leaving veteran Dennis Kelly and rookie Isaiah Wilson to fight to be the starter at right tackle.

Fortunately, there isn't as much turnover along the offensive line as last season, when both guards Rodger Saffold (free agent) and Nate Davis (rookie) were new additions. It took a while for last year's offensive line to jell into the dominant unit they were toward the end of the regular season and into the playoffs.

A tough six-game stretch to start the season -- which includes trips to face the Denver Broncos and Minnesota Vikings in addition to hosting the Pittsburgh Steelers and Buffalo Bills -- won't leave much time for this year's offensive line to work out the kinks, but Smith aims to take another step forward in his second season as offensive coordinator. Tannehill believes the odds are in the Titans' favor to do so.

"Having a bunch of guys back is a big benefit for us, especially at the skill positions because we have a lot of experience with each other," Tannehill said. "We can make some big strides this year going into, with Arthur [Smith], with me, with a bunch of the guys, our second year together."