January 14, 2015; Oakland, CA, USA; Golden State Warriors center(12) fights for a rebound with Miami Heat center(21) during the first quarter at Oracle Arena. Mandatory Credit: Kyle Terada-USA TODAY Sports

The Golden State Warriors are the talk of the NBA. They’re the proud owners of the best record in the league, and are winning games at an incredible rate. It’s hard to find a weakness when it comes to the Warriors, as they’ve been playing a near-perfect brand of basketball lately.

However, over the past few games, I’ve noticed something that might come back to hurt the Warriors in the playoffs. The once-impervious Warriors may actually have an Achilles’ heel after all.

The Warriors played the Utah Jazz, the Miami Heat, and the Oklahoma City Thunder in their last three games. All three teams have one thing in common: they play with a double-big lineup. The Jazz started Enes Kanter and Derrick Favours, Miami had rookie Hassan Whiteside and Chris Bosh, while OKC played Serge Ibaka and Steven Adams last night. Those were the players Draymond Green, Andrew Bogut, and Marreese Speights had to handle.

And here are the results:

GSW Rebounds (OFF Reb) OPP Rebounds (OFF Reb) GSW v UTA 31 (6) 44 (11) GSW v MIA 36 (10) 41 (11) GSW v OKC 43 (13) 54 (16)

For context, OKC leads the league in rebounds, Utah are 19th, Miami are dead last, and the Warriors are eighth.

That’s right: the Warriors were somehow outrebounded by the league-worst Miami Heat. Looking at the league stats, the Warriors are actually doing quite well when it comes to their rebounding numbers for the season: they are second in the league for defensive rebounds per game (34.5), 24th in offensive rebounds, and eighth overall.

However, a simple month-by-month filter shows distressing results.

Note: I’ve disregarded October due to the small sample size.

Month Rebounds (OFF Reb) DEF Reb Rank OFF Reb Rank Reb Rank November 45.1 (9.0) 2nd 27th 4th December 45.1 (11.1) 6th 13th 7th January 41.7 (10.3) 22nd 19th 22nd

The steady decline in rebounds per game could be attributed to one thing: Andrew Bogut’s absence. Bogut started missing games on December 10 and only returned on January 7. While Bogut was healthy, the team averaged 45.9 rebounds per game, 10.2 of which were offensive rebounds. With him gone, that number dropped to 44.5 rebounds per game, with 9.8 of them being offensive boards.

Dec 6, 2014; Chicago, IL, USA; Golden State Warriors center Andrew Bogut (12) and Chicago Bulls forward(16) fight for a rebound during the first quarter at the United Center. Mandatory Credit: Dennis Wierzbicki-USA TODAY Sports

The on/off numbers for Bogut continue to support the hypothesis that his removal worsens the Warriors’ rebounding ability: when he’s on the court, the Warriors gather 77.4 percent of their defensive rebounds, and only 71.2 percent when he sits.

The issue here isn’t the low number of offensive boards for the Warriors. Coach Steve Kerr has prioritised transition defense over crashing the offensive glass, and even then, the Warriors are only 20th in the league in limiting their opponent’s fast break points per game (13.7 per game).

The problem here is the defensive rebounding. The Warriors are the best defensive team in the league, allowing just 97.3 points per 100 possessions. They are also the league’s best team at limiting their opponent’s field goal percentage, allowing just 42.3 percent shooting.

However, the defensive possession doesn’t end until the defense successfully rebounds the ball. And don’t look now, but the Warriors’ opponents obtain an offensive board at a 26.6 percent rate – the eighth highest in the league.

Unfortunately, this is a by-product of playing a small-ball lineup. Having Draymond Green as the power forward in the starting lineup creates matchup issues for the opposing team’s bigs, especially when they are uncomfortable with venturing out to the three-point line. He draws defenders away from the basket and creates space for his teammates, and if defenders don’t respect his range, he drops three-pointers like it’s no one’s business. Just ask the Chicago Bulls.

However, he also struggles against the same, bigger opponents on the glass. He’s a tweener: too big for the small forward spot, but too small for the power forward position. And opponents take advantage of the size difference by averaging 12.0 offensive rebounds per game when he’s on the court. That said, he’s not the worst offender.

Feb 10, 2014; Oakland, CA, USA; Golden State Warriors power forward Marreese Speights (5) and Philadelphia 76ers power forward(50) both jump ahead of the ball on a rebound during the first quarter at Oracle Arena. Mandatory Credit: Kelley L Cox-USA TODAY Sports

Marreese Speights, the fill-in starter for Andrew Bogut, allows 13.2 offensive rebounds per game when he’s on the court. That’s the fourth highest mark in the team, and isn’t something you want to see from your starting center. For all the good work that Speights has done this season, he still suffers slightly on the defensive end. He contests shots well and is attentive when it comes to his rotations, but can still be found ball-watching instead of fighting for a rebound. He tends to wait for the rebound rather than fighting for position and sealing off his opponent – something they teach big men from day one.

And if ever you needed proof of what Andrew Bogut does defensively, especially when he isn’t filling up the box score, here’s some: Bogut is the team’s best when it comes to limiting offensive rebounds, allowing just 11.0 offensive boards per game.

So what does that mean for the Warriors moving forward? The Warriors have been linked with signing a backup big man, in case Bogut goes down with an injury (which isn’t unlikely). Jermaine O’Neal is a fan favourite, and while his name has been mentioned frequently lately, there are other suitors involved as well. The front office is in a precarious position: should they address the team’s need and risk messing up the team chemistry, or should they just wait it out and see?

September 27, 2013; Oakland, CA, USA; Golden State Warriors shooting guard(20), center(10), and center(31) talk during a TV interview during media day at the Warriors Practice Facility. Mandatory Credit: Kyle Terada-USA TODAY Sports

The team doesn’t seem to have an internal solution to the problem at hand. David Lee, the other big man on the bench, is also too small to be considered a consistent rebounder against bigger opponents at his position. Festus Ezeli, the backup center, is still out with an injury, and is far too injury-prone, despite making considerable improvements to his game. Which leaves Ognjen Kuzmic – the less said about him, the better.

The Western Conference features a lot of teams that play a double big-man lineup. The Portland Trailblazers, Memphis Grizzlies, Houston Rockets, San Antonio Spurs, and the Thunder all feature bruising big-men combinations that punish smaller teams. The Warriors can rely on their run-and-gun game, but it’s well known by now that the pace slows down in the playoffs. Being able to complete their defensive possession with a rebound is going to be important for them, and if Bogut is out, the stats so far don’t tell a very flattering story.

The Golden State Warriors seem unstoppable right now. But, take a closer look at the team, and you might just find a few fine cracks in their armor.