I'm going to stick my neck out here and say that the term flavor as used in brewing is a bogus concept. What you sense in the mouth is taste; what you sense in the nose is aroma. That covers everything - there is no third sense of flavor.
How do you define the difference between taste and flavor?
Taste is what you sense with your taste buds: salt, sugar, acid, bitterness, umami. As far as taste is concerned, hops only affect the bitterness receptors. Aroma is what you sense with your olfactory bulb inside your nose, whether it gets there via your nostrils or around the back of the soft palate while food/drink is in your mouth.
How you define flavor is up to you - maybe some combination of taste and aroma that is experienced only when something is in the mouth, perhaps. That's fine, but it's still just a combination of taste and aroma, so there isn't any scientific logic in splitting hop additions into taste (start of boil), flavor (middle of boil) and aroma (end of boil (aroma). That's not to say the mid boil addition is pointless - it might well be doing something. But it's very misleading to describe flavor as equivalent to taste and aroma.
Personally I think of flavour as aroma alone. Mint flavour, orange flavour, strawberry flavour... these are all compounds detected inside the nose. I would never describe something as salt-flavoured, acid-flavoured or bitterness flavoured.