Spy actions also have an influence on over-all leaderboard, also believe battle losses too. But basically its easy for a newer account to get on ally lb, value and even battle - if someone spends a lot, but on over all leaderboard, length of time playing comes into its own
I always thought overall was total stat strength: build + BFE + BFA. Personally I don't understand why bws would be included - that's why there's a battle win leaderboard in my opinion. For instance, the All Star Wars are limited to the top 10k players. Why should the amount of battle wins matter when making the ASW cut? Regardless, apparently it's a thing.