When the Houston Rockets unveiled their “jumbo” lineup on opening night, hopes were high that they could build one of the most impenetrable defenses in the NBA.

With a starting lineup featuring five players listed 6-foot-7 or taller — including Defensive Player of the Year candidate Amen Thompson — plus capable defenders like Tari Eason, Josh Okogie and Clint Capela off the bench, Houston had enough size and athleticism to match up with anyone.

The Rockets lost their first two games, but they’ve since bounced back with consecutive blowout wins while putting together some dominant stretches, including Wednesday’s 139-121 victory over the Toronto Raptors.

While their massive lineups have played a significant role in their recent success, the defense has been somewhat of a disappointment. Houston, which finished fourth in defensive efficiency last season, sits at No. 19 after four games this season.

Instead, Houston’s offense has been the catalyst. The Rockets are No. 1 in offensive efficiency (125.2 points per 100 possessions), exploding for 276 points in its last two wins — and they are doing this without their experienced floor general Fred VanVleet, who tore his ACL weeks before the start of training camp.

Yes, it does help that the Rockets’ last two games have come against the Raptors playing without starting center Jakob Poeltl and the Brooklyn Nets with … whatever personnel they’re putting on the floor these days.

Still, Houston’s early offensive success is a promising sign, considering Kevin Durant is still working to acclimate his skills within the system and the team is ironing out shot-creation responsibilities without VanVleet.

Here are some of the primary reasons behind Houston’s early offensive explosion:

Point Şengün

Alperen Şengün came into this season as one of the NBA’s premier-playmaking big men, but he’s taken his game to another level as his responsibilities have grown without VanVleet.

Through four games, Şengün is averaging 23.8 points and 7.3 assists — both career-highs — and he’s basically taken over the point guard duties while still operating as one of the most potent low-post scorers in the league.

Earlier in his career, the 23-year-old often picked teams apart with his passing while operating at the elbows or on the low block. Now, Şengün’s bringing the ball up and handling it in pick-and-roll situations as much as any guard on the roster.

Şengün has received the “Baby Joker” comparisons since the moment he stepped into the league, and he is taking full control of the offense like Nikola Jokić by punishing teams from every area of the floor.

Who needs tiny point guards eating up possessions when you’ve got a 6-foot-11 athlete making plays like this off the dribble?

The offense sometimes slows down as Şengün methodically works his way to his spots. But his efficiency has been impressive considering how much more he’s floating around on the perimeter.

The Rockets have outscored opponents by a whopping 61 points when Şengün is on the floor. And that still doesn’t necessarily capture how important he is to everything they do on both ends of the court.

With the addition of Durant, one of the main questions surrounding the Rockets coming into the season was how much Şengün was prepared to be the second superstar Houston needs to compete with teams like the Oklahoma City Thunder and Jokić’s Denver Nuggets.

It’s still extremely early, but Şengün looks to be up to the task so far.

KD living up to the hype

Considering the amount of young talent on this team and the success it had last year, there was no overselling how massive it was to add Durant. It transformed Houston from a fun team with some potential into a full-blown title contender.

However, for all those expectations to be met, Durant needed to demonstrate that he could still consistently carry a winning team as the No. 1 option. To this point, he’s been exactly what the Rockets expected him to be on and off the court.

Through four games, he’s averaging 27.5 points on 52/37/85 shooting splits despite having a career-low usage rate (25.7 percent). He’s been very calculated about the moments when he tries to impose his will on the offense and when he allows the young guys like Şengün and Thompson to take over.

If anything, it probably would be better for everyone involved if he put in more of a conscious effort to tell folks to give him the ball and get out of the way.

Durant has clearly come into this situation with a deliberate plan to build up the younger guys around him and encourage them to take ownership of the offense, rather than looking at him to do everything.

One of the main concerns following VanVleet’s knee surgery was how much of a toll — physical and mental — the 37-year-old Durant would have to endure to keep this offense afloat for the first few months of the season. How much could the Rockets ask of Durant while also expecting him to perform at an elite level once the playoffs begin?

The good news is that Durant clearly feels comfortable picking his spots with his new teammates, and he’s leaving enough room for guys like Thompson, Eason and Reed Sheppard to take control when necessary.

Another sign that Durant is feeling good and consistently putting pressure on opposing defenses: He is averaging 9.8 free-throw attempts per game. He hasn’t averaged more than nine free-throw attempts per game for an entire season since 2013-14. Şengün, additionally, is averaging 8.5 free-throw attempts per game, by far the most of his career.

Houston isn’t settling for jump shots and stagnant offense. The Rockets are playing in transition, getting to the rim and forcing opposing defenses to make tough decisions.

Although they’re still learning each other, Şengün and Durant are already one of the top duos in the NBA.

Leveling up on offensive glass

Last year’s Rockets grabbed offensive rebounds at a historic rate; this year’s team has managed to do it at an even greater rate so far.

In their first four games, the Rockets are grabbing rebounds on 42.9 percent of their misses. That’s tied with the Utah Jazz for No. 1 in the league. The Rockets finished No. 1 last year by a wide margin when they grabbed an offensive rebound on 36.3 percent of their misses.

That inflated 42.9 number might not stay that high all season, but Şengün, Thompson and Steven Adams are capable of dominating the offensive glass against most opponents. This opens up some of the most efficient shots an offense can create, whether it’s putbacks around the rim or kick-out 3-pointers.

Once again, the Rockets are among the top teams in the league at scoring on second-chance points and in transition. They can dominate teams with their size or their athleticism — or both.

For the most part, the Rockets have been impressive with their offensive execution and their early understanding of how to complement each other. That should only improve with time as Durant has more opportunities to learn his teammates’ tendencies and mentality.

The early returns have shown that this Houston team has a few statistical advantages that will make it a difficult matchup for most opponents. And if Durant and Şengün keep playing at such a high level, the Rockets will be a problem in the Western Conference.