There is one huge problem with the current leaderboard system: having no all-time rankings makes the ranking system useless. What's the point of the ranking system if you don't even know who the best player of all time really was? With the current weekly system, all you have is the player who goes on a hot-streak. You don't get to see who plays really well consistently and who truly deserves respect in arena matches.
The weekly system isn't bad, but it would be nice to see which players are truly the best of them all. That's why we should have two sets of leaderboard rankings: all-time and weekly. Having the overall and weekly rankings would give players chances to be the best player of all time and at the same time see the players playing particularly well throughout the week.
Note: If the all-time rankings only portray the players that play the most, then that the ranking system should be changed. The points can remain to judge the winner in a match, but not to determine the best players. I suggest a kill-death ratio to determine the best players. It will eliminate the points gained from other players' deaths and consider only the players' skill in the game.
I think this issue needs a bit more attention than it is getting before it can be laid to rest. Now, I found it very reasonable to reset the ranking points the first time - but resetting it every Sunday like they are has made the leaderboard utterly meaningless. Why is there a leaderboard if it will be reset weekly? Do those on the top 10 get some kind of reward for being there when the weekly reset occurs? No, they don't. There is no reason for a leaderboard at the moment.
In my opinion, I feel that there should no longer be weekly resets at all. There's no reason for them. Fixing the previous problems with idlers was a good move, and I appreciate it, but with a weekly reset that fix means absolutely nothing to me. I have no interest in resuming Blast Network or reclaiming my old position on the top 10 with the weekly reset in place. Wasn't the first reset necessary to make sure all players once again had a fair chance against each other on the leaderboard with idling no longer being a problem? Why continue to do it?
Also, I like your idea of changing the current ranking system so that those who play best are on top, rather than those who play most frequently. A good ranking equation in my opinion would be to take one's overall kill/death ratio and compare that to the number of overall games they've played. This would serve as an accurate depiction of how well one does in all games on average. However, removing the weekly reset should come first.