its not just height but also the strength specially the legs and arms thats important in selecting a center. a bull-strong 6'8" guy will box-out anytime a weak 7 footer.
Thats why Japeth is best at the small forward position to create mismatches against his smaller defender. in addition his thin body does not make him ideal guy for the center or power forward position. in contrast, look at 270 lbs Asi Taulava, he is only 6'9" , but he was able to hold his own against much taller but skinnier Asian centers.
from my experience guarding taller guys, a 4 or even 6 inch height difference is not a big deal as far as me pushing him out of his comfort zone as long as he is skinny and weak

of course, it becomes a big problem is the guy is not only taller but also stronger, then the only realistic thing i can do is position myself between the ball and him , and hope his outstretched hands doesn't catch the overhead pass before your sundot(deflect), and/or double-team help from a teammate. other than that, just hack his shooting hand but that won't work in a real game as you'll foul out quickly.
the problem in all the philippine national teams is not only the height but the body strength of our centers and power forwards. Try reviewing the videos of gilas against foreign middle-east teams, and youll see the big difference in body size/strength. observe closely how skinny Japeth aguilar is compared to that star lebanese power forward(forgot his name). Thats why even though Angola is a short team, they are still competitive because even though they are about the same height as philippine teams specially the past powerade teams, they are strong
since japeth is skinny but athletic he is ideal for transition attacks, fastbreaks, pick and roll drives to the basket, etc but not for isolation power plays ala Shaq because he will just get pushed out.