I mean, you have to set the cut-off somewhere. I picked 28 points per 36 as it seems in the same ballpark of "elite volume" as Harden's 32.3 and Steph's 31.7, but you could also look at 25 or 20, and/or use the more traditional PPG.
Either way, Iverson is — rightly — never going to be anywhere near the top of any list of efficient scorers. He's one of the least efficient high-volume scorers ever, with a career TS of .518, and only one season out of 12 where he broke .550. In his highest scoring season (2001-02), he rocked an atrocious .489 TS.
Fwiw,
here's the all-time TS% list if we make it an even 20 PPG minimum (and a minimum 1500 minutes played). First thing that jumps out is more appearances by Barkley and McHale.
@wade boggs chicken dinner As noted above to HRB, "points per fga" is really dubious measure of scoring efficiency. It basically assumes that getting fouled and hitting one of two free throws is a more efficient use of a possession than, say, a four-point play. Or put another way: it assumes that if you get fouled when shooting, it's more efficient to miss the shot than hit it. ;-P