I suppose you can make the argument that Big Boss really did descend into villainy. This is a man who raised nuclear weapons for practically no good reason, screwed up the life of some medic, getting countless innocent people killed in a hospital(seemingly with no regrets or guilt), putting an entire army in that medic's hands despite the likely psychological instabilities from the identity crisis, shrapnel injury, and hypnosis, stealing that man's identity, screwing over his friends and allies, all so he could selfishly hide and raise another army with nuclear weapons. The guy's a psycho.
And his descent into villany happens offscreen. Which sucks monkey balls.
We go from the guy from Peace Walker's ending to Ishmael who sets his own men for certain death.
How?
And he dares to wear a jacket with the Diamond Dogs logo on it.
Uughhh... >_<