Why is your "big game" definition more valid than my "big game" definition.
I can easily define a "big game" as 30-12, and if Love continues at his current pace, he'll have many, many more of those than KG. Similarly, I can diminish the importance of scoring in my "big game" definition and up the importance of blocks and assists and say that anything above a 20-10-5-2 game is a "big game," of which KG, as you pointed out, leads the field. Using your logic, KG has had more "big games" than Hakeem.
So, here's Midnightpulp's arbitrary big man "big game" definition:
At least 20 points, 15 boards, 3 blocks, on 50% shooting.
http://bkref.com/tiny/6dWnV
Duncan ranks 3rd all-time since 1986, and has triple the amount of those games as Barkley.
Relativism, do you understand it, mother er?