I believe he had a slight injury that he tried to play through as well, which didn't help. But basically he wasn't given a chance to get all of the suck out of his system. Look at a bunch of the young players in the league. Look at Buddy Hield, at Brandon Ingram, at Wiggins, at Dennis Smith, at Lonzo Ball. The list could go on and on- for every Ben Simmons, there are at least three or four players who struggle a bit their first few years.
I want to say though that through out all of this, we have barely if ever heard anything negative out of him- and that is something at least. He seems like a good kid, and, even though he is very unlikely to be on the team next year and seems less and less likely to put it all together as each season passes, I can't help but hope that he does.