No new ground covered here.
Jahlil is in a horrible situation for his skillset and, it seems, his personality. The team around him is not constructed to help him succeed, and he doesn't have the tools to make that team better.
High usage rookies almost always make their teams worse. Lots of words have been generated about how Jahlil has failed to carry the terrible Sixers out of the depths. I haven't read much about how ineffective Emmanuel Mudiay has been. Deangelo Russell isn't winning games for an NBA team anytime soon, either.
I suspect it has something to do with the other two high profile rookie big men in this draft, who have been really good and have helped their teams compete more often than anticipated. Jahlil is almost certainly not ever going to be on the same level as Towns, and he may never have the two-way impact and versatility of Kristaps. But I think that says more about how strong the top of the 2015 draft was than it does about Jahlil.
Personally, I look at that Philly situation with Okafor in the inverse way -- I continue to be really impressed that a rookie, recently 20 year old big man can be averaging so close to 20-10 despite having so little offensive skill around him, on a team whose only competent point guard is Ish Smith. I mean, for goodness sake, look at the shooting percentages of the guys who share the floor with him.