That and sophomore PJ from a physicality standpoint was much stronger than what IT will be as a freshman. Even as a freshman, PJ came in with a sturdy base and a lot more muscle on him.
And as you eluded, the personnel surrounding PJ + Painter's offenisve philosophy really masked PJ's height and lack of athleticism, and really did so all 3 years as a starter. PJ wasn't asked to be a dynamic PG at Purdue because with AA, Biggie, and Haas commanding the post 3 consecutive years, you didn't need a dynamic PG. IT will not get that luxury as a freshman.
IT will play PG at Purdue, but that is because of his size. He is a more natural 2 guard, but his size doesn't translate to a 2 at the college level. IT undoubtedly is taller, more athletic, and a better scorer than his brother, but he doesn't have the pure PG skill set that his brother had. And at 6-0, 160 lbs, an underclassmen IT is going to struggle mightily creating his own shot as well as taking bigger, stronger defenders off the bounce, and showing a 1:30 highlight tape on the other thread of him primarily catching and shooting in an AAU game with poor close outs and defensive rotations isn't going to change that narrative. It doesn't mean he is "bad at basketball" either, it just means he has a lot of work to do in terms of getting his body ready for B10 basketball. The same kind of things are being said about Trevion Williams and what he needs to do to get into playing shape to really be an effective basketball player, yet you don't see anyone else citing that as a reason he "isn't good at basketball".