I wouldn't exactly call venom snake a success if we assume that he rebels and it's eventually ordered to be killed by big boss. Obviously, I'm assuming a lot of things here because I still need context
It's not made clear whether he rebels or not in these spoilers. Not that it really matters, both outcomes are utterly moronic. I've pointed out the fallacy in the real Big Boss sending Solid Snake to kill him. It makes no sense in any way, shape or form.
We still don't know who really created Outer Heaven. Big Boss? Faux Boss? Both? For a game that was
all-fucking-about Outer Heaven it failed and I still find it utterly incomprehensible that Big Boss has managed to form so many armies that end up butchered. His "legend" amounts to everyone under his command getting killed.
Portable Ops handled Big Boss as a military leader so much better. Peace Walker was him getting into the groove of leadership. We've received none of that since, V's contribution is just "he's a bit of an asshole" which we knew already, and it fails to show us how he became that asshole, because all of the asshole actions are perpetrated by an evil twin. Creating that evil twin in the first place is simply not enough.