To me there are 4 high ceiling guys: Simmons, Dunn, Bender and Ingram. That is what my board would look like BPA-wise. I MUCH prefer drafting Dunn to Hield or Brown. Those would be the worst choices at 3. Murray I have mixed feelings about. Dunn is goung to be a stud, I think his game screams NBA more than college whereas Hield I feel the opposite, better collegiate game.
Being already 22 I wouldn't but Dunn on a highest ceiling list. I personally think that based on physical potential and skills that need to be added I would put Simmons, Chriss, Brown, Bender, Baldwin, Maker and Ingram as the highest ceiling guys in this draft. Guys like Dunn, Hield, Valentine and Sabonis are high floor players due to their already developed skill set and clear NBA roles.
I think we sometimes get lost on the fact that 22 year old players aren't done growing. One of dunns listed attributes is his enormous upside due to his combo of size, athleticism, playmaking, and defense. I do the same thing all of the time. I look at a slightly older player and immediately diminish his potential.
However, diminished potential in older players tends to stem from a lack of some elite quality. Players who are super athletic or talented in one particular area tend to jump ship before they get to that 21/22 year old area. The ones who make it to their senior year tend to make it to the nba due to a perceived "intangibles or coachability. Or they light up kids younger than them, while having obvious flaws.
Those qualities don't really apply to dunn. His upside is still there.