It seems to me (from this and other questions), that you're misreading the nature of bridge. There is no "clear, objective, expert" answer to "What do I bid with this hand?". If it were "What does American Standard say I should bid with this hand, assuming Pass from RHO?", then it would probably reach the standard for SE sites, but even soit's still not Objectively answerable; your bid should be affected by the vulnerability and whether you need a good result or are happy with an average (and probably will be affected by your estimate of your partner's and opponents' abilities).
On the other hand, if you asked "What is the reason you can overcall with a weaker hand than you need to open?" I'd say that's a fair question (although not one I'd be inclined to answer; you really need to read a book on your system).