The Rockets have the first 10 seconds of a possession figured out. Their problems surface in the back half of the shot clock, when things slow down. The freedom and aggressiveness they play with at the start of a possession can devolve into disorganized stagnation at the end. When the shot clock is short, the Rockets can appear to lack a plan beyond putting Harden in a pick-and-roll — never a bad option.

This was the case in Tuesday’s loss, and the frustration in the locker room was evident.

“Our spacing tonight was not very good,” Parsons said with a growl. “We didn’t do anything to help anyone else.”

The Rockets know they can play better, more together. They did so for a solid 20-game stretch last month. But as the playoffs near, the Rockets are still chasing a level of consistency necessary to advance against the likes of the San Antonio Spurs.

“We thought we were over it,” Harden said of the Rockets’ injury issues. “Getting guys healthy. Getting into a mojo and a groove.”

Playing without Howard and the starting point guard Patrick Beverley, who is out with a sprained right knee, obviously does not help matters. Beverley is a fine offensive player and the N.B.A.’s pre-eminent point guard pest. McHale called him a “very gritty, tough kid.” Beverley and Howard pose a formidable defensive battery: Beverley harasses the perimeter, and Howard smothers anything that reaches the paint.

But as a team, the Rockets tend to lose focus on defense. Harden is the worst offender. Despite his size, athleticism and coordination, Harden is a technically unsound defender who is often caught napping when his man does not have the ball. Though he can more than make up for his defensive failings with his superlative offense, it is difficult to form an effective defensive identity when the team’s best player is a defensive sieve.

Perhaps Harden’s best defensive quality is all of the free throws he makes, because they give the Rockets more time to set their half-court defense.