I’ve had it with professionals whining about not knowing their roles.

What does that even mean? This ain’t Hamlet. It’s the NBA. You show up. You take open shots. You pass to the open man. You rebound, you run your butt off, you ice your knees, and then you go home.

Shake Milton, a G League commuter, dropped 39 on Kawhi and the Clippers on Sunday. Milton was poetry in motion. He didn’t need lines, or makeup, or a dressing room with a star. Shake didn’t plumb the depths of Claudius’s depravity in Los Angeles. He just balled out.

Al Horford and Glenn Robinson III, listed much higher on the nightly playbill, combined for 14 points in a painful 43 minutes. Horford was hired as Embiid’s understudy, mainly to be a steadfast defender. There was no question of his role Sunday. And then backup forward Montrezl Harrell cooked Horford for 24 points.

This resounds all the more in this moment because of the malcontents’ recent chorus of dissent. Something is rotten in the state of Pennsylvania.

First, Horford, in December, bellyaching about his new coach not optimizing his allegedly underused offensive skill set. Then Robinson arrived at the trade deadline and, after playing just six games, he whined that he hadn’t been told what his role was. Also last week, after a gutting loss to a lousy team in Cleveland, Josh Richardson said the team lacked “heart.”

Combined, these complaints from Sixers newcomers paint a picture of disarray on a team coached by Brett Brown and helmed by general manager Elton Brand. Each player arrived this season from a well-respected organization. Horford was the veteran glue for Danny Ainge and Brad Stevens in Boston; in his sixth season, Robinson had finally broken out for Steve Kerr in Golden State; and Richardson spent his first four seasons in Miami under Erik Spoelstra and president Pat Riley.

So, might there be something to all this? Yes, and no.

Yes, the Sixers function in an irregular manner. The young All-Stars, Joel Embiid and Ben Simmons, dictate their own development and participation, a circumstance created by improper fraternization with the ownership group that undermines the authority of Brown and Brand.

But no: The way the Sixers function does not excuse the way Horford and Robinson have played. This has become ever more obvious since the Sixers lost their young All-Stars to injury.

Milton, a second-year, second-round project, made his 12th NBA start Sunday. He’s starting in place of Simmons, the point guard with the bad back, but Milton has replaced the scoring of Embiid, who left in the first quarter three games ago with a shoulder injury. In those three games, Milton is averaging 26 points, and during Sunday’s 136-130 loss, Milton tied the NBA record for consecutive made threes, with 13. Not once did Brown call a timeout and explain to him when or how to shoot. He knew his role: get buckets.

Embiid, healing at home, appreciated the performance.

Tobias Harris has figured out his “role,” too. Harris is usually the No. 3 offensive option and he was averaging 18.9 points before Embiid joined Simmons in the training room. Harris is averaging 29.5 points in the last two games, and he had 25 against the Clippers.

Robinson had two points. He had averaged a career-high 12.9 points in 48 games with the depleted Warriors, but Sunday was the worst representation of his talents since his arrival.

“I showed them what I could do [at Golden State] ... I don’t really understand it," said Robinson, a pending free agent, told Basketball Insiders last week. "I’ve got a family to feed.”

That family might starve. He’s 0-for-10 on threes in his eight games. The number 26, Milton’s average in his last three games, is relevant for Robinson, too, since it’s his point total since the All-Star break. His post-break average is 4.3. He has started four of those games.

Brown usually avoids conflict with his players, but he deviated when Robinson blamed his poor play on Brown’s strategy.

"That is not true,” Brown said last week of Robinson’s claim. "After the All-Star break, every single one of them got a road map: ‘This is your role. This is what we expect done.’ ”

As a 33-year-old, five-time All-Star given a guaranteed $97 million over four years to be Embiid’s mentor, backup, and what Brown calls “the adult in the room,” Horford’s betrayal was far worse.

“I’m very limited with the things that I can do,” he said Dec. 30, when asked why he was scoring just 12.6 points on 46% percent shooting. “Ultimately, we have to rely on [Brown] to make the decisions.”

Brown eventually decided to bench Horford on Feb. 11, but, because of the injuries to Simmons and Embiid, that lasted only three games. So, remove the principals and Horford should return to form, right? Given more chances, he should put up the same numbers he’d averaged the past three seasons: 13.5 points, .498 field-goal percentage?

Nope. He’s scoring 11.0 points and shooting 41% percent in his four starts. He scored 12 points and fouled out Sunday.

That was not his role.