I think both fleet and Individual scores should be posted. The particular formula should be simple. Keep a to 25 leader board in certain catagories. Healing, Damage, Wins/loses, for example. Weekly and overall leaders could be posted as well. Creating a complicated persistant pvp scoring system for non persistant pvp is ilogical. I would rather have persistant pvp over persistant pvp scoring.
I definitely think the only good thing to track for an actual "rank" of a player should be whether he won a match or not. Winning a match requires teamwork. It doesn't require the highest DPS or healing, just that you win.
I have no issue with also tracking other statistics, like average DPS, healing per match, death to kill ratios, and the like. But it doesn't really tell if you're a good player. It might tell us a plaer's strength or weaknesses, though. Is in a lot of winning matches, has top DPS and kills, but a lot of deaths? You should see if you can lend him some support when you fight on his side, and don't worry so much about bringing damage yourself, that's what he will take care of.
Question might be how would one actually rank "wins" so that newcomers have a chance?
Would we measure something like Matches/Wins as a score? Or Wins:Losses? Per player or per character? Both?
Or do we track the stats over time and count the last, say, 10 matches fully, and then every 10 or so at 20 % less weight?