I like very much the feature that tells you, in the weapon/vehicles stats, in which part of the leaderboards you are (top X%).
It would be nice to add, just beside the top X%, a little arrow, green for up and red for down, to see how you are progressing with the specific weapon/vehicle.
It could be done with a regular update: for example every day a check is done and the ranking of the day is compared with the ranking from the day before and then a green or red arrow appears.
Maybe you could have better idea to implement these comparisons.
I think this would generally increase the challenge of bf3 very much.