Joel Embiid arguably could be one of the most gifted athletes to don a 76ers uniform.

He's a 7-footer who dunks with ease off between-the-legs moves. He's a once-in-a-generation athlete for his size. He has the natural talent to develop into one of the NBA's best players.

But he'll need a good work ethic combined with an ability to stay healthy to turn that potential into results on the court.

"There were times that I wasn't happy," coach Brett Brown said Thursday of Embiid's lack of diligence. "And you know it's been well-documented."

Embiid's work ethic has been questioned by some inside the organization. The whispers ended after the center started doing on-court drills in March.

However, a blow-up with assistant strength and conditioning coach James Davis was one of the reasons Embiid was sent home during a West Coast road trip in December.

After he underwent surgery for a fractured right foot in June, Embiid missed his entire rookie season while rehabilitating his leg.

Early on, the Cameroonian was limited to activities such as using the antigravity treadmill and taking long walks to generate a rapid heart rate. In the process, he became noticeably heavier than the chiseled 250 pounds he carried in his lone season at Kansas.

He has since lost some of the added weight. But another problem was that he wasn't always a willing workout participant, according to sources. He even blew off conditioning drills, one source added.

An altercation with Davis during the West Coast trip, coupled with Brown's wanting him to be in "more of a structured, stable environment," prompted the Sixers to send him home, the sources said.

"If you can't coach your best players, I call it buying time and dying," Brown said. "You have nothing. . . .

"I tell my guys, you want me to coach you. You want to show up on time. You want to do the right thing. You want to act the right way."

Brown said Embiid was no different from Nerlens Noel a season ago and other young players who are unable to participate. Noel sat out the 2013-14 season to rehabilitate his surgically repaired left knee.

"To put a person in a canoe and don't give them a fishing rod is pretty frustrating," Brown said.

Embiid has regained his spirit since participating in on-court workouts. Brown said he doesn't begrudge him or Noel for being frustrated about not playing.

"It's my job to coach them and build a culture," Brown said of the 21-year-olds. "That's what we experienced this year, and we will be better off for it just like we saw with Nerlens, who is actually a playing member of the Philadelphia 76ers."

Embiid's foot, however, is still a major concern.

There's a chance this injury will hinder Embiid's career the way it has for other 7-footers. Like Embiid, Yao Ming suffered a stress fracture to the navicular bone - in 2008 and again in 2009. Yao eventually was forced to retire in 2011 because of the injury.

"It's always a concern," Brown said. "I attribute it directly to his weight."

The Sixers talk to Embiid constantly about his diet. They believe Embiid understands that excess weight takes a toll over 82 games of pounding and running rim to rim.

"Through my voice it has been delivered almost as fear," Brown said. "It should scare the hell out of him. This is his future."