One online sportsbook recently pegged the Texans’ over/under win total for 2018 at 9.5—a number eclipsed by just five teams, all of whom make up the list of obvious Super Bowl favorites. Those early odds reveal an awful lot of optimism around a squad that won just four games last year, and that swing’s clearly because of the anticipated return of Houston’s two most important players: quarterback Deshaun Watson and defensive lineman J.J. Watt.

On one hand, a nine-to-10-win range feels like a conservative starting spot for a team whose offense exploded under Watson last season and whose defense with a healthy Watt could return to its elite status. But on the other hand, an extraordinary amount of uncertainty around the duo remains—and not just from an injury point of view. It’s tough to expect Watson—who will be running what head coach Bill O’Brien is calling “a totally different” offense—to keep pace with his rookie performance, when he tossed 19 touchdowns in seven games. And it’s anything but a given that the 29-year-old Watt, who’s generated just 1.5 sacks in eight outings over the past two injury-shortened years, will ever return to form as a Defensive Player of the Year–caliber force.

That wide spectrum of possibilities makes the Texans one of the most unpredictable teams in the league this year, so let’s take a deeper look at just how right, or wrong, things could go. Here are actually realistic best- and worst-case scenarios for both Houston units in 2018—and what each scenario could mean for the league at large.

The Offense

Best Case: Watson surpasses last year’s breakout performance and the Texans offense blasts into the stratosphere.

In the six-game stretch from Week 2 (Watson’s first official start) to Week 8 (when he tore his ACL), Houston scored an NFL-best 208 points—an average of 34.6 points per outing. Extrapolate that over a full season, and the Texans would’ve finished with the sixth-highest scoring offense in league history. Watson’s presence as both an aggressive downfield thrower and a runner created a conundrum for opposing coordinators, who had to choose between committing extra resources to the front seven to protect against designed QB runs and the plethora of screens Houston’s offense deployed or dropping more defenders back deep—an area of the field in which the rookie attacked without fear (a league-high 20.4 percent of his passes went 20-plus yards downfield in that stretch, per Pro Football Focus). Including the season opener, in which Watson took over for Tom Savage at the half, the former Clemson Tiger threw 19 touchdowns and eight interceptions to compile a 103.0 passer rating—and added 269 yards and two scores as a runner. At that rate, Watson would have finished the season with 43 passing touchdowns and over 600 yards on the ground.

Not shabby for a rookie—and given a full offseason to learn the playbook, plus a full load of all those crucial first-team reps during training camp (for which he is expected to be cleared) and preseason, it’s not wild to envision Watson—and by extension, Houston’s offense—picking up this year where they left off in Week 8. That influx of new plays into O’Brien’s updated playbook could give the Texans the ability to keep teams on their proverbial heels all year too.

Of course, Watson’s got a pretty strong support group: DeAndre Hopkins (who caught a league-high 13 touchdowns last year) remains one of the most consistently dangerous red zone targets in the NFL; Will Fuller is as dynamic a deep threat as any player in the league; and Lamar Miller gives the team the foundation for an effective ground game. The offensive line is still a major question mark, but that may not matter much anyway; heavily utilizing pre-snap motion and the quick passing game helped Watson survive and thrive behind a porous group last year—he was the most pressured quarterback in the league, per PFF—and he can do it again in 2018.

If Watson makes a jump in Year 2 (hell, even if he just plays at around the same level as last year), the sky’s the limit for what this Texans offense can achieve. With that unit dropping 34-plus points a game on opponents, even an average performance from the defense could make Houston major contenders not just in the AFC South, but in the conference at large.

Worst Case: Defenses catch up to O’Brien’s schemes from last year, the “new offense” doesn’t work, and Watson regresses badly.

It’s probably a stretch to expect Watson to match the ridiculous touchdown pace he set as a rookie. In those seven games, he threw 19 scores on 204 attempts for a 9.3 percent touchdown rate. For reference, just two quarterbacks in the modern era have broken the 9.0 percent mark over a full season: Peyton Manning during his MVP year in 2004 (49 touchdowns and 10 interceptions) and Ken Stabler in 1976 (27 touchdowns and 17 interceptions). So, it’s not so much a question of whether or not that number will fall; it’s by how much—so Watson needs to avoid the sophomore slump in other key efficiency metrics like yards per attempt (8.3 in 2017) and completion percentage (61.8) in 2018 in order to keep Houston’s offense from falling flat.

Part of that challenge will depend on the health of Watson’s knee: Right out of the gates, he’ll have to prove he can still plant and throw downfield with accuracy following last year’s season-ending ACL tear. Past that, if the team wants to use him as a runner less often, he may need some extra help from Miller and the ground attack to keep defenses off-balance. But behind the team’s cobbled-together offensive line, a strong run game is no given. Nor is the idea that O’Brien’s playbook, whether it resembles last year’s or draws on something completely different, will continue to confound defenses with heavy doses of motion and play-action.

Ultimately, I doubt Houston’s offense can get worse than what we saw under Tom Savage and T.J. Yates. But if they significantly regress from what the team did under Watson for those six weeks last year, the team’s potential playoff run could become a pipe dream. That is, unless the defense makes a big jump forward ...

The Defense

Best Case: Watt turns back into a DPOY-caliber player and becomes the capstone to a dominant Texans defense.

It’s easy to forget that for a few years, Watt might’ve been the best overall player in the NFL. In 2014, he racked up an NFL-best 20.5 sacks, an NFL-best 119 pressures (holy crap), 10 passes defensed, and grabbed an 80-yard pick-six—oh, and he caught three touchdown passes, too. He was completely dominant, is what I’m saying, and made plays from all over Houston’s line en route to the Defensive Player of the Year award. That Texans defense finished sixth in defensive DVOA (they ranked fourth in weighted DVOA, which means they got stronger as the year went on), seventh in points allowed (19.2 per game), fifth in opponent passer rating (80.4), and seventh in both net yards per attempt (5.9) and yards per attempt (6.7). In 2015, Watt reprised his role as the most unblockable player in the league, grabbing an NFL-best 17.5 sacks, NFL-best 92 pressures, eight passes defensed, and three forced fumbles. That squad finished eighth in Football Outsiders defensive DVOA, tied for seventh in points allowed (19.6), and tied for third in net yards per pass attempt allowed (5.6) and yards per attempt allowed (6.6).

Houston’s overall defensive performance has slowly dropped off over the past two years, most of which Watt has missed with back and leg injuries. In 2016, the team ranked ninth in defensive DVOA and 11th in points allowed (20.5); then in 2017, it fell to 23rd in DVOA and ... dead last in points allowed (27.3). The Texans defense still has a strong foundation: Jadeveon Clowney has emerged as a star, and there’s plenty of talent and depth in the secondary, but it’s a group that’s really missed Watt’s pass rush up front. Football is a team sport, but top-tier defensive units operate with a delicate equilibrium—and subtracting an elite player from even the deepest group can still create a major snowball effect on performance (turns out it’s just not easy to replace 100-plus pressures). A healthy Watt (who is expected to take part in training camp) has the ability to take over a game in a way that few defenders can, and dropping the peak version of that guy onto what’s already a talented defensive squad in Houston could help the unit ascend to elite status.

Oh, and if the Texans get the peak version of Tyrann Mathieu—another former DPOY-caliber playmaker whom the team signed in the offseason—Houston really could challenge the Vikings and Jaguars for defensive supremacy in 2018. That type of rebound could even make Houston a Super Bowl contender.

Worst Case: Watt remains the shell of the player he once was, Honey Badger fades, and the Houston defense continues to fall.

After undergoing back surgery to repair a herniated disc in the summer of 2016, Watt—even when he’s been on the field—just hasn’t looked quite as explosive as he was early in his career. If that version of Watt shows up again in 2018, he won’t be enough to fix a unit that really struggled last year. Injuries were a part of Houston’s problems, sure, but those losses exposed a lack of depth on the front seven, where the team missed a bevy of dependable role players like Brian Cushing, Brooks Reed, Jared Crick, and Vince Wilfork.

As for Mathieu, Houston’s banking on the idea that slotting him into one role—safety—will be exactly what he needs to get his career back on track. Only, early on, the Honey Badger was best as a versatile weapon who could be deployed all over a defense, playing as a de facto slot cornerback, safety, or a box linebacker on any given snap. That unpredictability was a big part of what made him so dangerous, so the Texans risk diminished returns by pigeonholing him into a single role (though Mathieu does sound optimistic about what that could mean for him this year).

With a subpar Watt and monotonous Mathieu, Houston could struggle on defense again in 2018. Even with Watson at his best, another down year from that unit could mean curtains for the team’s hopes for contending; remember, during Watson’s incredible six-game ascent last year, Houston still lost three of those games (to the Patriots, Chiefs, and Seahawks) thanks to a defense that gave up nearly 40 points per defeat. That type of no-show on that side of the ball, especially against playoff-caliber teams, just won’t cut it in 2018.