I have to argue that he is big-O Orthodox because what else is he? He's obviously not a vagante--he has real Churches and over 25 bishops with real dioceses behind him--but he is not in communion with the rest of Orthodoxy. Was the Bulgarian Orthodox Church "not Orthodox" when it was out of communion with the EP? I personally don't think so, although others might disagree. What about the Macedonian Orthodox Church? It's certainly schismatic but not non-Orthodox.
I have to wonder: perhaps we need to distinguish between Canonical Orthodox, Schismatic Orthodox, and Non-Orthodox, because I think it is a bit of a pull to claim the UOC-KP is not Orthodox (with a big O); while we must acknoledge that Filaret is a schismatic, it is claimed he is deposed, etc. I don't think it's the Catholic POV at all--namely that grace runs from consecrator to consecratee--because the emphasis is NOT on whether Filaret is a "validly consecrated bishop"--the issue is that he was consecrated by Orthodox bishops for an Orthodox Church (ie his local diocese, Metropolia, and Autonomous Church) but he chose to act outside of his jurisdictional mandate and so is considered schismatic. That's a lot different than if a mentally senile old man such as Met. Vitaly consecrates a deposed priest to be a bishop, and this new bishop doesn't even have any parishes to back him up!
So in other words, I am arguing that one does not have to be in communion with world Orthodoxy to be an Orthodox bishop (I mean obviously one should, but human problems such as Patr. Alexy and Patr. Bartholemew make it difficult on hierarchs sometimes). For instance, say one day Metropolitan Philip decides to break union with the Patriarchate of Antioch and joins the OCA. Then everyone excommunicates the new OCA-Antiochian merger. Does that mean that this Church is no longer Orthodox? Hardly. Irregular? Yes. Schismatic? Maybe. Non-Orthodox and on par with Bishop Billy Bob of the True Cathodox Apostolic Word Church of God in Christ? No!
Another thing to think about: in 1996 Moscow broke communion with Constantinople for about a month. Did Moscow cease to be Orthodox for a month? I don't think so. Now they were in communion with the other Churches still, but I think this whole "I'm in communion with A, A is in communion with B and C, etc" is a relatively new idea. I could be wrong of course, but I just don't see that as normal.
I'd shy away from making any kind of formula for Orthodoxy and simply say that some signs one would look for in an Orthodox Church would be
1) Orthodox faith as measured by the Scriptures, Ecumenical Councils, etc.
2) Orthodox episcopate, ie an Orthodox bishop was consecrated by other Orthodox bishops for an Orthodox community (and not in someone's living room for instance to be the Bp of Main Street, Boise, Idaho)
3) Communion with the other Orthodox Churches
with #3 having the caveat that such could be lacking provided there was an extinuating (sp?) circumstance, which would place said group in a suspect, irregular, and possibly schismatic position, but which would not automatically disqualify it.
Violation of #2 would make you a vagante,
Violation of #1 would be the Roman Catholic position for instance.
Another analogy my friend just made was that if your finger gets cut off, it's still alive for awhile; it can be reattached, and in the meantime it's still you. So maybe for awhile, the KP or Macedonians, or whatever are still Orthodox, but it depends on their orientation: if they try to reenter communion with the other Orthodox, they will be ok, but if they turn inwards, they will wither and die.
These are just my thoughts and I haven't worked them out totally yet, and it's something I struggle with.