Could also just be that the monk is in absolute dungeon BiS with a handful of warforged items giving him exactly the right stats he needs and those 5-to-10 ilvls above him have stats all over the place and are energy/rage/mana starved, not getting procs and generally suffering from lack of reforging combined with a low number of sockets in which they can be fairly tiny +stat gems that make virtually no difference while eating food that is no better than it was before.
Guess we'd have to check that same group when the Monk is in raid gear.