But what advantage would you have out of a higher Battle Value? You just get into fights against better, and better, and even better people by time. Your opponents will be so OP compared to you by time, that you can't do anything in those games, even if the other 9 players may cause you win the match. Like you are Level 10 and fight against Level 30's. Even if your team win, totally no fun.
I'm actually happy if my BV goes down and down, so i get into easy games by time where I can own everybody
However, in a preview Screenshot they showed how BV is displayed ingame. A character had 3200 points, and it showed BV of 320, another had 2000 points and it showed BV of 200. Since those were probably new, never used before demo characters and they had like no BV, I guess it's points/10 that somehow gets into the BV. So the best man in the looser team is pretty close, or even higher, like the worst of the winner team. But how it all works in detail, don't know. But we will see on Monday, as we can observe our own BV development.
Edit: And I think it's too obvious to even mention it: If you join a running game that is over within few seconds, and you take place of one of those "oh i loose i leave" guys... it MUST NOT have any effect in battle value.