I don't think you understand the argument. If you're going to say that Biyombo is 6'8" and use that to justify him not being a C (because he's shorter than other Cs), then you have to use the other Cs heights barefoot as well. For instance, Dwight Howard measured out as 6'9" without shoes on DX. You must use THAT measurement to compare the heights, not the 6'11" that Dwight is listed at (because that is inflated with his shoes on). So rather than being a 3" difference between the two, it's only a .69" difference.