With Kevin Durant's early-season health concerns and head coach Billy Donovan's acclimation stage, the Oklahoma City Thunder didn't have the greatest start to the 2015-16 NBA campaign.

The Thunder got out to a mere 3-3 record through their first six games and a mediocre (for the powerful West) 7-6 record through 13.

They struggled with solid opponents and feasted on those with defenses weaker than their own. During that time, Durant failed to find his groove while Russell Westbrook continued the offensive onslaught he displayed a year ago absent the former MVP, Durant.

But those times are history -- well, kinda.

Offense

The Thunder -- since their November 20th loss to the Knicks -- have gone 14-4 in their last 18 contests and have appeared to recapture the dynamic offense we saw from them in their Western Conference Finals just a few years ago.

In fact, with the offensive improvements of Westbrook, OKC's offense is operating at an even higher level to this point in the season. They're averaging over a point more per game, with 107.9, and are nearly a point better in terms of Offensive Rating, with 111.3 points per 100 possessions. 

They trail only Stephen Curry and his ridiculous Golden State Warriors in those two categories. So, you could easily make an argument that Oklahoma City is the second best offensive team in the league.

Just take a look at how they compare to San Antonio and Cleveland, the other two teams (outside of Golden State) with better records than Oklahoma City.

On a nightly basis, the Thunder score a lot more points than the likes of the Spurs and Cavaliers. However, the gap narrows a little when it's taken into account over a 100-possession sample size for Offensive Rating. The reason why is that the Thunder operate at a substantially higher pace of play, as they average 96.0 possessions per game compared to the Spurs' 93.7 and the Cavs' 93.0 -- both of which fall within the bottom six in the entire NBA.

Nonetheless, the Thunder are a better offensive team. The dynamic duo of Westbrook and Durant make them the second best offensive attack in the game. But, as the numbers indicate, they aren't as far and beyond the Spurs and Cavaliers.

In the eyes of Offensive Rating, the Spurs are the third-best offensive team in the league. Oh, and the Cavs are just now playing with Kyrie Irving at the point (albeit for limited minutes).

I -- along with many others -- would expect their offensive numbers to rise with the gradual release of Kyrie's offensive skills. The trio of Kyrie, LeBron James and Kevin Love are going to be a force to be reckoned with in the last 50-plus games.

So, as we can see, the Thunder have a very good offense that places them among the elite. But what about defense?

That is where the doubts lie.

Defense

What the Thunder boast offensively on one end of the floor, they lack on the other end of it.

The Warriors, Spurs and Cavaliers rank third, first and sixth in Defensive Rating, respectively -- none of them giving up more than 101.4 points per 100 possessions. The Warriors, with their blazing pace, allow an understandable 102 points per game, while the Spurs and Cavs surrender a mere 88.8 and 95.3 points a game (first and second in the NBA). 

The Thunder rank outside the top 10 in both Defensive Rating (102.8) and points allowed per game (99.6). But on the bright side, the Thunder rank third in defensive rebounds per game (35.4) and fourth in blocks per game (6.5).

Oklahoma City is really good at defending the paint, as they hold their opponents to 58.2% from 0 to 3 feet -- tied for second in the NBA. But despite their elite rim protection and high rebound totals per game, the Thunder give up the eighth most offensive rebounds per game, at an 11.4 per game clip. That's better than the Warriors (who probably don't care all that much about that stat) but way worse than the Spurs and Cavs. 

They're giving up valuable additional possessions. If they were to limit those, they might see their opponents' Effective Field Goal Percentage of 47.4% go even lower. That's how this Thunder defense has operated, as they don't force many turnovers (they are 22nd in the league in doing so). 

This Thunder defense has shown promise in many ways, and maybe they haven't even hit their stride yet. With a little improvement on the defensive boards and a concerted effort to force more turnovers, the Thunder might just sneak into the top seven or eight defenses in the league. For now, they're not quite that, which is easy to see after they surrendered 112 points to the Nuggets a night ago.

Overall

We know that the Thunder are a top offensive attack but that their defense leaves a little to be desired from a championship contender. The Spurs, Cavaliers and Warriors all take pride in their defensive efforts just a little bit more, and they have the stats to show for it.

To this point in the season, the Thunder have the third-highest nERD (a ranking that is predictive of a team's ultimate winning percentage on a scale of 0 to 100) total -- 74.4 -- of all NBA squads. That's ahead of the Cavaliers by 11.3, which is a sizable drop-off from the top three teams.

You might be saying, then, that the Cavaliers are the fourth-best team and that the Thunder are ahead of them as title contenders.

I mean, we'd have to agree since we have OKC at an 8% chance of winning the title and Cleveland with a 6.2% chance.

Where everything gets kind of grayer is where we look toward the future a little more. The Cavaliers are working Kyrie in now, and barring any setbacks, he should be in good form within the next month. And if that's the case, we could see three 20-plus point scorers on a nightly basis in Cleveland.

That would, without a doubt, improve the Cavs' offensive output and efficiency down the stretch.

Until that happens, the Thunder rate third among the Association's top teams, behind only the 1A Warriors and the 1B Spurs. They may not be the elite of the elite, but with some improvements on defense, they sure could be. If they do, it's sure going to be a lot of fun watching the three Western powers duke it out for the top three seeds in the Western Conference playoffs and beyond.