Just for fun I went and avraged out the career points, rebounds and blocks numbers (per 36 minutes) for all NBA players ever to play who were at least 7'3" tall.
The list of players included (including scrubs) is:
* George Muresan (7'7")
* Manute Bol (7'7")
* Shawn Bradley (7'6")
* Yao Ming (7'6")
* Chuck Nevitt (7'5")
* Pavel Podkilzin (7'5")
* Slavko Vranes (7'5")
* Mark Eaton (7'4")
* Rick Smits (7'4")
* Ralph Sampson (7'4")
* Priest Lauderdale (7'4")
* Randy Breuer (7'3")
* Keith Closs (7'3")
* Zydrunas Ilgauskas (7'3")
* Peter John Ramos (7'3")
* Arvydas Sabonis (7'3")
* Ha Seung-Jin (7'3)
* Hasheem Thabeet (7'3")
There is a single player (Swede Halbrook, 7'3") who I have not included because he played in an era before blocks were recorded.
The average numbers for all players 7'3" and over are:
* 14.7 PP36
* 9.6 RP36
* 2.9 BP36
If you filter that to include only players 7'4" and over the numbers are:
* 14.2 PP36
* 9.5 RP36
* 3.3 BP36
If you filter it again to include only players 7'5" and over the numbers are:
* 13.75 PP36
* 9.63 RP36
* 3.75 BP36
Yao Ming's career numbers are:
* 21.0 PP36
* 10.2 RP36
* 2.09 BP36
What I take from this is...
1) Yao was a good scorer, scoring about 43% more than the average for players 7'3" or over. In fact his scoring numbers per 36 minutes tops the list, with the next best being Rick Smits (20.0 PP36) and Peter John Ramos (19.8 PP36).
2) Yao was right about average as a rebounder for his size. He averaged only 7% more than the average >7'3" player, which is a negligible considering half of the guys on that list were scrubs who nobody has likely heard of.
3) Yao was significantly below average as a shotblocker for a big man. He averaged 28% fewer blocks than the average >7'3" player, and about half as much as the average >7'5" player. In fact the only players who averaged a lower block rate at 7'5" or taller were Pavel Podkilzin and Slavko Vranes, who aren't even worth mentioning considering they played a combined 31 career NBA minutes. It's safe to say that Yao was the worst shotblocker ever to play at 7'5" or taller.
So this makes it a bit easier to evaluate Yao as a player - he is a very good scorer, an average rebounder, a below average shotblocker. At 6'10" on a per 36 minute basis I'm thinking he probably would have averaged about 18 points, 8 rebounds and just under 0.8 blocks.
Comparison # 1 would be a Chris Bosh but without the athleticism
Comparison # 2 would be Dirk Nowitski but with about 20%-30% less offensive ablity
Comparison # 3 would be a current day (i.e. 37 year old) KG minus the defensive instincts
So sure, he'd still be a pretty good player and probably a borderline All-Star, but not an All-Time great. Maybe he'd be about on the level of Al Hortford or Lemarcus Aldridge.
I've always thought of Yao as being overrated, and I still do. I've always known he's good, but people spoke about him as if he was arguably the best center in the league and one of the greatest ever, and I never saw that. To me has nothing on the likes of Dwight and Bynum (when healthy) or the elite centers of yesteryear (Shaq, Ewing, Robinson, Hakeem). I honestly think he was a 'good' center who was massively overhyped as a result of his size and the fact that he was Chinese.