Opponents have been boxing out and out-rebounding the Rockets this season. (Bill Baptist/NBAE via Getty Images)
The math had seemed simple enough in Houston: Take a team that ranked second in the league in defensive rebounding rate the season prior, add one of the league's best overall rebounders in Dwight Howard, and enjoy a healthy advantage on the glass. That Omer Asik, himself the second-best defensive rebounder in the league last season, was set to play a major role alongside Howard also seemed to position Houston for thorough rebounding dominance. The two towers had been assembled, strength was piled on strength, and if nothing else the Rockets seemed equipped to scoop up defensive boards and jump-start their frequent fast breaks.
Yet something in that very basic calculation went horribly awry, to a degree that few could have anticipated. Not only has Houston failed to trounce teams on the glass this season as expected, but a new roster dynamic seems to have come at a crippling rebounding cost; in a single bound, the Howard-led Rockets have cratered from the second-best defensive rebounding team in the league to its third-worst.
Those troubles began with Houston's now-defunct big lineups -- featuring Howard and Asik as a tandem -- which flunked their way through the early going for a variety of reasons. Most surprising, though: That supersized group struggled to rebound at any remotely acceptable level. With the pairing of Howard and Asik on the court, the Rockets failed to meet even their pitiful season average on the defensive boards, affording opponents additional scoring opportunities on 30.6 percent of their own misses. That's a brutal allowance, particularly from lineups constructed around the interior strength of two conventional bigs.
So what gives? Naturally the individual rebounding numbers of both Howard and Asik have taken a dive when the two play together, as one would expect given the competition for rebounds between them. Beyond that, it's clear that Howard and Asik never fully understand how to defend as a pair, which then served to hinder their ability to work the glass. With both Howard and Asik accustomed to being a primary, self-sufficient help defender, the two often rotated over to challenge a shot attempt in the paint at the same time. That kind of blunder left two opposing big men unattended near the hoop as a shot went up, an easy recipe for an offensive rebound. The joint instinct to help against penetration is a good one, but neither Howard nor Asik seemed to have a firm enough grasp of how the team's defensive principles played into their relationship as interior defenders. One was tabbed a power forward and the other a center, yet fundamentally they were looking to carry out the same job.
Even that doesn't fully explain why these big-driven lineups would be so atrocious on the defensive glass, though there are enough complicating factors to help make some sense of the mystery. Houston's general defensive sloppiness has certainly done Howard and Asik no favors, as they're often pulled in unexpected directions to contain all kinds of gambles and letdowns. Jeremy Lin, Patrick Beverley, Francisco Garcia and Aaron Brooks also offered no rebounding help whatsoever in the Rockets' big lineups, totaling just two defensive rebounds between them in 179 combined minutes, per NBA Wowy. Asik's rebounding dropped the most significantly between the two bigs, and one could see hints that his once buoyant effort level would fall into dips and lulls when playing with Howard. It's some combination of incompatibility, unfamiliarity and diffusion of responsibility, and in total it compromised what seemed to be an apparent strength for this lineup.
Since Asik was moved to the bench (or out of the rotation, depending on the day), second-year forward Terrence Jones has stepped into a larger role as a starter. He's off to an impressive start (Jones has averaged 15.8 points, 9.2 rebounds, and 2.2 blocks per 36 minutes), though has proven to be a bit of a rebounding liability due to his disinterest in actually boxing his man out. It's not uncommon to see long, athletic players skimp on the fundamentals of rebounding, but Jones is particularly guilty of surrendering interior position to his mark and attempting to control a rebound with his arms alone:
Given that, it comes as little surprise that the Rockets grab a smaller percentage of possible defensive rebounds with Jones on the floor (69.3) relative to when he sits (73.2). By failing to properly box his man out, Jones often forces players like Howard into a difficult choice with the ball in the air. Howard has his own, often bigger opponent to contend with on the glass, an effort which will already require his full attention. Yet he now also must be mindful of the fact that Jones has let his man get the slip on him inside, which could be a problem if the ball takes a bounce in that direction. With an opponent in prime offensive rebounding position and Howard caught between two opposing bigs, Jones' faults tend to come at a cost.
Now that Jones has played more than a third of the Rockets' total minutes this season, that's starting to become a problem. Solutions, though, remain elusive. Houston's most successful rebounding lineups this season have been smaller, scrappier units that can only be used selectively. Much of what troubles Houston's rebounding efforts otherwise are matters of personnel or process -- neither of which can be remedied quickly. Still, the Rockets sit at 10-5 with the fourth-best pace-adjusted scoring differential in the league. This is not an issue that will unravel a contender at the seams, though there's room nonetheless to fully appreciate the problems such lackluster rebounding may pose. Such is the weight of a title-contending expectation, as Houston's every flaw must now stand up against rigorous postseason scrutiny.
Statistical support for this post provided by NBA.com.