Duncan is a good point. I think Duncan was a PF until Robinson retired, transitioned and has been a C since. This hurts the argument for Duncan as best center or best PF - since his career is split.
Shaq was a pup when he played Hakeem head to head whereas Hakeem was at the height of his powers. LAL Shaq was a beast and submitted numerous
top 25 PER seasons.
Seasons of top 25 PER all time
Jordan: 7
Shaq: 5
Wilt: 3
Lebron, Robinson, Kareem: 2
Wade, McGrady, Chris Paul, Garnett: 1
Hakeem's best is 64th all time.
I think you have to factor in intangibles, defense, and championships. But Shaq brings a lot of those. Negative points for not winning another title or two in LAL and being a part of the blow up, but no C's fan can take Kobe's side. Shaq was also mobile enough then to be an anchor on defense. And those LAL teams had Kobe, but the rest of the roster wasn't that great.
Just going by that first team Glen Rice was the third best player with a 16 per and 31 MPG. Everyone else was below average (15) PER. No one else averaged more than 30 MPG (or more than 25.5 MPG).