PHILADELPHIA – The 76ers opened their home season without Joel Embiid and Paul George in uniform, a disappointing start to a promising season. It was easy to understand why George wasn't out there.

Geroge hyperextended his left knee during preseason training. He needs time to recover, that's natural.

But why exactly isn't Embiid playing?

“The plan is why he’s not playing,” Sixers coach Nick Nurse said. “He hasn't re-injured himself, but the plan is that we don't feel like he's quite ready, strong enough, light enough, whatever it may be. You've noticed that he's not quite ready to go yet. Never been to a court hearing, etc. And that’s the plan.”

This past week, “The Plan” was chanted loudly throughout Philadelphia. The Sixers have a plan for Embiid to get on the floor and not get injured. They don't publicly explain how it works, what determines his readiness and why he hasn't crossed the threshold to play in more than two months since Embiid represented Team USA at the Paris Olympics.

The NBA will likely launch a formal investigation into Embiid's absence, two sources said The athlete spoke on condition of anonymity because they were not authorized to speak publicly. ESPN was first to report the possible investigation.

League policy requires healthy players to be available to play. Embiid has been listed as out for this week, while George will be re-evaluated later this week.

Embiid has not had any notable injuries of late. While undergoing knee surgery last winter, Embiid played in the playoffs for the Sixers and then competed fully for Team USA in the Olympics.

A Team USA source said Embiid was never injured during the Olympics. He fell ill before Team USA's Olympic opener and had to sit out the second game of that tournament, although not because of an injury. This ramp-up phase has dragged on so long that the mystery behind the process has once again caused consternation from outside.

Doc Rivers knows how this process works. The Milwaukee Bucks coach was Nurse's predecessor in Philadelphia. He had to answer the same questions the nurse is answering now. The problem is that there is no magic way to keep your superstars healthy.

“You don’t. You can't do that. There is no secret,” Rivers said. “I was here for three years and Joel was never healthy in the playoffs. Joel didn’t do anything wrong.”

Embiid is a walking paradox, a dynamic scorer disguised in the body of a giant. Rivers has learned from experience that while Embiid has pushed the limits of the game to become one of the best players of his era, his body has to pay for it.

“Joel is a big guy and he moves like a guard,” Rivers said. “There are days in training when he takes a step and you say, 'That's not normal for a big guy.' And so his body can say that too.”

Tyrese Maxey reacts after falling to the ground in the fourth quarter against the Bucks. (Bill Streicher/Imagn Images)

This becomes even more apparent when you see how much the Sixers struggled to put together a clean performance in their 124-109 loss to the Bucks on opening night. They took 98 shots – 18 more than Milwaukee – but shot 12 percentage points worse. Without George and Embiid, Tyrese Maxey scored 10:31 in 39 minutes as he and Kelly Oubre Jr. tried to carry the offense on their shoulders.

Maxey acknowledged that he played poorly overall and addressed how he felt he played rushed offensively and struggled to find the right balance to make contact when attacking the rim.

This led to the question of what was simply described as “that feeling.”

“What feeling?” Maxey asked.

The sentiment underlying the question is, unsurprisingly, the knowledge that the 76ers have struggled without Embiid. It's a recognition of their 16-27 record without him last season. The reminder that while they are one of the best teams in the league when their MVP is on the field, they are the underdogs when he is not on the field.

“We played a game. “I’m not going to sit here and say we played bad just because Joel was out,” Maxey responded. “Yes, we didn’t win the game, which is the ultimate goal. But we were without Joel for most of the preseason and all of training camp. He’s on the rise, so we need to go out there and implement what we’ve been working on.”

With Embiid currently only out for next week, there is currently no fear that they will have to find their identity without him. The 76ers need to find a way to play consistently in his absence. He is already scheduled to miss almost 20 games due to his stress management plan.

Even if they are better prepared for his future absences if he misses back-to-back, that doesn't change the fact that they are a very different team without him. Their offense is taking a different shape and their defense can't just pass the ball to their rim protection and expect everything to be taken care of.

Paul George, who injured his left knee in the preseason, watches the season opener against the Bucks. (Jesse D. Garrabrant/NBAE via Getty Images)

Nurse talked about wanting to see his team more physical and even encourage them to push off when the defense is reaching for them. They need to set the tone with their physicality when Embiid isn't out there to do that for them.

“It can’t just be because of Joel Embiid that we win. “It’s just not possible,” Maxey continued. “There's no championship team that just insists: If Joel doesn't play and we lose every single game, we can't win that way. I feel like we need to have good chances tonight and continue to play the right way to get better.

“I’ll definitely feel better, so I won’t worry about it.”

(Top photo of Joel Embiid in civilian clothes dribbling the ball during a timeout: Bill Streicher / Imagn Images)