Embiid has a chronic knee problem which affects his work on his fitness.
His work ethic can't be that bad considering how skilled he is despite starting to play basketball at a very late stage.
I guess he, as many others, have tremendous work ethic on the fun parts. Shooting, dribbling, technical stuff. I'm sure he works very hard, as any professional athlete, but it's obvious he doesn't work hard
enough. If he did, he would last longer in these games where he has to do more on his own. The good thing is that it's very fixable. Stamina can be improved with some quite simple methods. The not so good thing is that it's hard work, and it's not fun. His knee issues makes it a bit more difficult, sure, but not impossible. There are examples of athletes who've lost serious time to injury, coming back in better physical condition due to focusing on that type of training and a proper diet.
Also, him starting to play basketball at a late age is impressive as feck. Really impressive, actually. But, could that be part of the reason for him not being better? I mean (it's a lazy argument, but an argument nonetheless), he's 7 feet tall, which is a relatively unique skill on it's own. But without athleticism it loses a bit of value. He knows he can dominate most players due to his height alone, and got used to that when he was first introduced to the game. He's never played the game while being "small" or young. Anthony Davis has mentioned the fact that he wasn't really that tall (relatively speaking) when he was younger has made him what he is today.
He's obviously very skilled, and a prototype modern NBA center, but he has to work on his halth and physique. Eat right and work out right. Not just more or "a lot", but right. And that requires dedication to it.
Even "Coca Cola" Jokic, notorious for his bad diet, has improved his physique and lost weight. Embiid did too, but has gone back to his old ways it seems. Apparently he lost 25 pounds of during the summer of 2019, but it really doesn't look like that now. I'm convinced that a good diet helps you stay healthy as well. Just look at Derrick "Gummy worms for breakfast" Rose. I don't have any evidence to back this up, but if he ate chicken breasts instead of gummy worms, could he have avoided a bit of his issues? Maybe. Maybe not. But there is a reason why most professional athletes take their diets as seriously as they do, it's not all about body fat %.
I just can't find an excuse for Embiid being a non factor after 7 minutes in a playoff game against a historical rival. If it's not about his work ethic, mentality and stamina, what is it? It's not all down to him being the best player as a center, his team isn't
that bad. And if he can't make any difference at all at this stage, he should 100% be traded. This also goes if he can't stay healthy, and his knees are the big issue. That means he can't be relied upon for any extended amount of time, and should be moved on.
Sorry for rambling about Embiid.