Troy Baker is not only the voice actor, but also facial performance actor for Ocelot in Metal Gear Solid V. This was confirmed on the Kojima Productions Alert 4, the official podcast of the studio.
Hideo Kojima and Troy Baker at E3 2013
Sean Eyestone: “We were looking for somebody who could hit that right range. Someone who is between young Ocelot and older Ocelot. And he just has a cool quality to his voice. And in addition to the voice acting skills he has facial skills as well.”
Source: KP Alert 4 (June 21 2013)