Fighter rank is the only rank that can possibly mean anything. Overall rank is just a puff piece obtained by accomplishing an annoying and tedious shopping list of chores. Fighter rank, however, especially the sub-stats that comprise it, can relate some useful information about the pilot and his plane(s). I've always contended that fighter rank itself is not important, but being effective is. The statistical illusion of effectiveness, via the fighter rank sub-stats, in the absence of any true skills, can only be perpetuated to a very limited degree without doing something dishonest.
So, for the most part, the sub-stats that comprise fighter rank can be a fair indication of someone's relative effectiveness. That being said, the best sticks in the game can destroy their sub-stats if they really work at it, making themselves appear as craptacular as they want to on paper if they really work at it (I rarely ever see a good stick do this). But, it's fairly impossible for someone with no abilities whatsoever to look like a fighter superstar on paper without resorting to unethical means.
Certainly, I will agree with some that have posted that superior fighter rank can very well have very little to do with 1 vs .1 turny bird DA type skills. A lot, if not the majority, of well ranked fighter pilots in the Late War MA, fly faster, relatively poor maneuvering late war planes, which are poorly suited to 1 vs. 1 duels with most other aircraft prevalent in the MA. The skill set required to be a MA tiger in a typical fast LW bird in the populous MA is quite different than that required to be a dueling King in Co-Alt/Co-E 5k Spits 1 vs. 1.
But, that's a far cry from saying anything like anyone who ranks well in fighters sucks and anyone who looks like crap on paper is really some kind of diamond in the rough. For the most part the sub-stats tell the tale in my observational experience. Those that look like crap-on-a-stick on paper are also crap when I have them in my piper. Conversely, those that look decent on paper are a good fight when I come across them in the MA. There's really very few excpetions to this other than the known cheaters or the career vulchers, but everyone knows who they are...