Here's what people constantly forget about the Sixers, they're pretty much the youngest team in NBA history. Imagine the Flyers if they did what some fans wanted and started this year with Sanheim, Morin and Provorov on defense, Konecny and AK as forwards, etc. And they'd still have a veteran corp.
NBA players, even the best, tend to hit their stride in their 4th season, few rookies make a serious impact, even the best players, especially the one and done players.
So when you look at the key players on the Sixers:
Okafor - rookie, just turned 20
Noel - 3rd year, but only 2nd year playing
Embiid - 2nd year, but no NBA experience
Saric - no NBA experience
Covington - 3rd year, but only 2nd year playing (D-league isn't the same)
Grant - 2nd year
Stauskas - 2nd year
Sampson - 2nd year
Holmes - rookie
McConnell - rookie
So your experienced players?
Ish - 22 career starts before this season
Thompson - 3rd season, 64 career starts before this season
Canaan - 3rd season, 21 career starts before this season
Which is why you have to look at these players in terms of development, not where they are right now. To say Okafor can't play defense after 41 games, is to say that despite his exceptional combination of size and feet, he can never learn positioning or anticipation. Anyone watching him can see the improvement, he can play big centers one on one and is getting better at reacting to the P&R. He's not going to protect the rim like Noel, he's also not going to get backed down in the paint like Noel.