The Oklahoma City Thunder are supposed to be in the running for a top-three seed in the Western Conference, but they sit at 0-3 following a miserable 131-20 home loss to the Sacramento Kings on Sunday.

Losing 108-100 on the road to the Golden State Warriors on opening night was nothing to be ashamed about. Neither was a 108-92 loss to the Los Angeles Clippers - especially considering All-Star point guard Russell Westbrook was sidelined those two games as he continues to recover from offseason knee surgery.

But losing at home to a lowly Kings team isn't acceptable. Giving up 131 points is inexcusable. The Thunder managed to lose by 11 even though Westbrook returned with 32 points, 12 rebounds and eight assists. Paul George had 29 points, six rebounds and three steals in the contest. And Oklahoma City still lost.

The OKC defense hasn't been great by any means, but it hasn't been horrible enough to warrant an 0-3 start. Per ESPN.com, they rank 20th in scoring defense - allowing 115.7 points per game. Teams have a mere .378 three-point shooting percentage against the Thunder, so it's not as though their coverage has been awful.

Credit: Alonzo Adams-USA TODAY Sports

With Westbrook, George and renowned defensive stalwart Patrick Patterson on the court, Oklahoma City's defense should be a top-tier unit. It hasn't been great by any means, but it's certainly capable of being better down the stretch.

One notable problem for the Thunder this far would be the limited production coming from the bench. According to HoopsStats.com, the Thunder are getting just 36.3 points per game - which ranks 16th in the NBA.

Teams like the Toronto Raptors, Boston Celtics and Utah Jazz have excellent secondary units, which is why they're off to great starts and will be forces in 2018-19.

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The Thunder don't have the same star power as the Golden State Warriors or Houston Rockets to get by without much of a bench. They simply need more out of guys not named Westbrook, George and Steven Adams.

The good news for OKC is that George, Adams and offseason acquisition Dennis Schroder are contributing plenty of offense. George has averaged a whopping 25.3 points, 5.3 rebounds and 3.7 assists per game. That's despite a porous .382 field goal shooting percentage. George will obviously get back to his regular shooting soon, which promises to boost OKC's offense even more.

Credit: Alonzo Adams-USA TODAY Sports

Adams continues to get it done as an above-average center. He's averaging 14.7 points and 14.3 rebounds per game. His defensive rating sits at a respectable 107. Adams has played up to his usual standards and will be a key piece of the Thunder going forward; they need him to sustain this play if they're to lock down another playoff berth.

The problem for the Thunder, is that their schedule isn't going to get much easier. They host the powerhouse Boston Celtics - who swept OKC in last year's season series - on Thursday.

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The Thunder should get by the Phoenix Suns at home this Sunday, but a home contest with the Clippers - followed by road game against the Charlotte Hornets and Washington Wizards - are not exactly gimme wins. Those are two talented teams whose respective offensive units could be too much for Oklahoma City to handle.

Let's keep in mind that this Thunder team did start out slow a year ago, however. Carmelo Anthony never gelled with Westbrook and George. Oklahoma City limped to a 4-7 start and didn't catch fire until mid-December, when they strung together a six-game winning streak.

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The Thunder stood at 22-20 on Jan. 10 of last season, but they found their groove and salvaged a 48-34 record. Westbrook and co. were upset by the Utah Jazz in the opening round of the postseason, but it's impressive enough they got 48 wins after a sluggish first three months.

So relax, Thunder fans. It's been a frustrating start, but this team could have been 2-1 had Westbrook not missed a pair of difficult road games. He looks to be in MVP form again, while George and Adams are still producing as expected. There is nothing to worry about when it comes to this team's top players.

The Thunder will eventually find momentum and get right back into the playoff race. But will they really contend for home advantage in the postseason? Only if the bench and defense improve, because Westbrook, George and Adams can't do it alone.

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