What are the early returns from the Houston Rockets' small-ball experiment? What can we expect from them in the playoffs?
When the Rockets dealt starting center Clint Capela for forward Robert Covington as part of a four-team trade before the deadline, it was clear that they were committing to starting 6-foot-5 P.J. Tucker in the middle. However, we assumed Houston would add a center via either another trade or the buyout market. When ESPN's Adrian Wojnarowski and Tim MacMahon reported that the Rockets would instead fill their last two roster spots by signing forwards DeMarre Carroll and Jeff Green, it became clear that Houston isn't going back to traditional lineups.
In the meantime, the Rockets have beaten two of the NBA's top four teams (the Los Angeles Lakers and the Boston Celtics) since adding Covington, with only one loss -- at the buzzer to the Utah Jazz -- in games they've played at full strength since then.
Can this really work? Can the Rockets win without a center?
How are the Rockets' small-ball lineups working?
Over the course of the season, Houston has played well but not exceptionally when going small. According to Cleaning the Glass, which factors out garbage time, the Rockets have outscored opponents by 6.0 points per 100 possessions with Tucker at center -- good enough to rank in the 80th percentile of all lineups.
However, it's worth remembering that for most of the season, Houston coach Mike D'Antoni was going to Tucker at center primarily when Capela was injured, taking one of Houston's best players out of the mix and leaving the Rockets with less depth to replace Tucker at forward. That changed with the Covington deal, which brought back one of the league's best 3-and-D contributors to fill Tucker's old role.
Since the trade, Covington and Tucker have played 205 possessions together (about the equivalent of two full games), and Houston has crushed opponents by 19 points per 100 possessions, ranking in the 100th percentile of all lineups. While it's no surprise that the Rockets have been awesome offensively playing five-out basketball, their 101.5 defensive rating with Covington and Tucker ranks in the 97th percentile.
The early returns don't suggest anything fluky about Houston's defensive success. Opponents have actually outperformed their expected shot quality based on Second Spectrum's tracking data but have been forced into tougher shots. The Rockets' quantified shot quality (qSQ) on defense, which tracks the typical effective field goal percentage (eFG%) for the location and type of shots as well as the distance to nearby defenders, has dropped from 52.6% (28th in the NBA) before the trade to 50.8% when Covington and Tucker play together (which would rank fifth over the course of the season).
Rebounding was an inevitable concern with Houston's small lineups, particularly given that Tucker grabs relatively few defensive rebounds. (In fact, the 16.3% of available defensive rebounds that he averages is below average for a power forward, let alone a center.) But the Rockets have secured nearly 79% of opponent misses with Tucker and Covington on the court rebounding by committee, a rate that would put them in the league's top 10.
Westbrook the beneficiary of trade
When Houston dealt Capela, the return wasn't just Covington. It also was an entirely different version of All-Star guard Russell Westbrook, who struggled when playing with Capela or another center (Tyson Chandler or Isaiah Hartenstein). Check out splits for Westbrook and James Harden, who hasn't seen the same kind of benefit from the change.
Remarkably, taking a center off the court and playing five-out lineups has turned Westbrook into the most efficient scorer he has ever been -- nearly as efficient as Harden. The best true shooting percentage Westbrook has managed in a season was .554 in 2015-16 and 2016-17, the latter his MVP campaign. As noted in the table, he is up to .607 when playing without a center this season. He also is scoring almost as many points per 36 minutes as he did en route to MVP (32.9).
Although Capela and Harden had strong chemistry as pick-and-roll players, that never developed between Capela and Westbrook. With Capela on the court, Westbrook's pick-and-rolls averaged just 0.84 points per chance, according to Second Spectrum tracking. That has skyrocketed to an even point per chance without a center.
Even more than that, Westbrook has benefited from having help defenders pulled away from the basket by the ability of all four other Rockets players to shoot the 3. Per Second Spectrum, 42% of Westbrook's shot attempts have come in the restricted area without a traditional center on the court, up from 27.5% with one. Westbrook is making those shots at a 69.5% clip, up from 55% when he played with a center. The combined effect means that Westbrook's made field goals in the restricted area have nearly doubled as a percentage of all of his shot attempts.
How might Houston go wrong?
The foremost concern is how much wear and tear playing center might put on the undersized Tucker, who has already carried an enormous workload. Since the start of the 2018-19 season, Tucker's 4,689 minutes rank fourth in the NBA. (Harden is second at 4,758.) That toll has only increased lately. In the seven games since Capela last played for the Rockets, Tucker has played at least 35:53 five times. The additions of Carroll and Green might help D'Antoni get Tucker more rest, and that's particularly important now that Tucker is defending bigger opponents on a regular basis.
Although Houston's switch-heavy defense mitigates this to some extent, Second Spectrum's matchup data indicate that Tucker is giving up more size. When playing with Capela, the weighted average for Tucker's matchups was 6-foot-7 3/10 inches and 223.4 pounds. That has increased while playing with Covington to 6-foot-8 1/10 inches and 232.7 pounds.
I'm somewhat less concerned about the possibility of teams exploiting Houston's lack of size by going to the post. Granted, we've seen a limited number of matchups, but so far only Anthony Davis has had particular success matched up against Tucker, scoring six points in 15 matchups as part of a 32-point game on 14-of-21 shooting. Among possible playoff matchups, the Lakers and the Denver Nuggets (with Nikola Jokic) are the two teams equipped to take advantage of Tucker's size.
I do wonder if, given more time during a series, postseason opponents can find better solutions to battle the Rockets' switches and neutralize Westbrook's dominant play. In their one-point win in Houston, the Jazz decided to put two-time Defensive Player of the Year Rudy Gobert on Westbrook, keeping him in position to defend at the rim against Westbrook and help off him at other times. Westbrook still scored 39 points, but he needed 33 shots to get there in a less efficient game than his typical performance without Capela.
As impressive as the Rockets' play has been since the Capela trade -- with the exception of a blowout loss at the Phoenix Suns on the second night of a back-to-back with Westbrook resting -- the odds are still against their returning to the Western Conference finals for the second time in the past three years. Houston wouldn't have home-court advantage in the first round if the season ended today, and it will be hard-pressed to climb out of the 4-5 matchup. That would mean a possible series against the conference-leading Lakers in the second round -- if the Rockets can advance.
Houston's small-ball lineups will likely get the blame if the Rockets fall short of the conference finals. However, this season's team was going nowhere in the playoffs with a more traditional lineup stifling Westbrook. Houston's bet on small ball has given the team far more potential for a deep playoff run.