OAKLAND — Giving up about an inch in height and 15 pounds in weight, Kevin Durant held back Pau Gasol with a forceful forearm, cleared an open pocket in the paint, flipped around while keeping Gasol on his back and then rose to snag the ricochet of a Tony Parker 20-foot brick.

It was a textbook box-out and defensive rebound, the third of Durant’s five in the season’s first seven minutes. Draymond Green had two. Stephen Curry had one. Despite some missed layups and sloppy play, the Warriors led 16-12 at the 4:20 mark of the first quarter, in part, because they rebounded all of the Spurs first eight misses, finishing out their defensive stops.

But that trend flipped quickly. The rest of the way, San Antonio missed 43 shots but rebounded 21 of those, a rate of nearly 49 percent. Last season, the NBA’s best offensive rebounding team (Oklahoma City) led the league at 31 percent. So this was a bludgeoning on the glass, lying at the heart of the Spurs’ shocking 129-100 opening night beatdown of the Warriors.

For Golden State, it’s a predictable and worrisome issue, though not to that extreme of a level. The Warriors rebounded 76 percent of their opponent’s misses last season, 15th best in the league, right around NBA average. Then they got slightly smaller at the center position this offseason, replacing Andrew Bogut and Festus Ezeli with Zaza Pachulia and David West, who both sputtered in their debuts.

But the 6-foot-11, wiry strong Durant is a massive rebounding upgrade over 6-foot-8, perimeter oriented Harrison Barnes. Durant had 10 of the Warriors’ 27 defensive rebounds on Tuesday night. So the reworked personnel isn’t primarily to blame for the massive rebound disparity in the opener. An uncharacteristic lack of effort and physicality is what stood out to Steve Kerr.

“Tape doesn’t lie,” Kerr said. “We didn’t box out numerous players where we got a stop and everybody just looked up at the ball and the rim, instead of putting a body on somebody and then chasing the ball down.”

A premium example came late in the second quarter. For the first time this season, Kerr deployed his souped-up Death Lineup: Curry, Klay Thompson, Andre Iguodala, Durant and Green. Together, they should terrorize teams that choose to keep lumbering big men on the court.

But it’ll be tough to exploit a massive skill and speed advantage if they can’t get out on the fastbreak. And it’ll be tough to get out on the fastbreak if they don’t gang rebound with energy.

Manu Ginobili missed a corner 3 with 75 seconds to go in the first half. As it bounced high off the back rim, Durant, Green and Iguodala were all in perfect position to seal off the lane, snag the loose ball and go. But Green and Durant stop, turn and stare, as Aldridge snakes through and outfights Iguodala for the rebound, which leads to two of San Antonio’s 26 second chance points. The Warriors only had four.

“Twenty offensive rebounds? That’s horrible,” Green said. “That’s 20 times we didn’t get out on the break. And that takes away, from this team, at least 30 points.”

Take a look at the lack of effort.

But even when the Warriors weren’t small, their bigs were having trouble. In 31 combined minutes, Pachulia and West only mustered five rebounds. Neither play above the rim, or even close, at this stage of their careers. But they’re typically more physical than they showed Tuesday night, carving out space and then plucking it down with a vice grip.

Pachulia, in particular, had some opportunities to grab a couple more. On one early third quarter possession, Kawhi Leonard drove past Thompson and drew help from Green. Leonard stopped and shot from about 12 feet out. As it hit the rim, in a freeze frame, all five Warriors are closer to the rim than any Spurs player.

But Curry and Thompson just watch as Leonard scoots by them. Then Pachulia, strangely, mistimes his jump, leaving the ground too soon and landing as it finally reaches a catchable area. Leonard beats everyone to the ball for an easy putback.

“We’re going to have to be a gang rebounding team,” Kerr said. “We can’t rely on somebody to just go get it. We have to make contact, be a more physical team, in terms of boxing out.”

Durant and Green rebounded generally well on Tuesday night and they must continue to all season. Iguodala, West and Pachulia didn’t, but they all have NBA track records that suggest this was more anomaly than trend. Curry is considered an above-average rebounder for a point guard. Thompson is considered below average for a shooting guard.

In the preseason, Thompson vowed to improve in that area. He said assistant Ron Adams has been pushing him to average around five this season. Thompson only had one in the opener and he was beat to several more, often by Aldridge after one of those early Warriors switches created a size mismatch.

“There’s times I was too lazy getting after those loose balls like I should’ve,” Thompson said. “Regardless if it’s October 25th, I need to play with more edge than I did last night, help out our bigs.”

In the first clip, watch Aldridge bulldoze right through Thompson into premium putback position (with little help from his teammates) and in the second clip, watch Aldridge on the back-side of the play, slide right in front of Thompson and seal him out of the play.

Rebounding won’t be a massive strength of the Warriors this season. But if the championship goal is to be reached, it can’t be this glaring of a weakness.

Klay Thompson on his role in the rebounding woes: "There's times I was too lazy" + his thoughts on ruining Zaza's behind the back dime pic.twitter.com/bwIYAIAmh8 — Anthony Slater (@anthonyVslater) October 26, 2016