Well to start with, I think every player on the leaderboard should have to play a minimum of 120 battles. That averages 8 per day. When I looked at the last Diamond leaderboard 19 out of the 40 winners wouldn't have qualified. In fact 5 of the top 6, and 7 of the top 11 played less than 100 battles (actually 1 was 102). To contrast that, there were only 9 of the next 60 ranks that played less than 120. In other words, the "winners" were the ones who didn't play very much.
The NBA has a 5 foul "bonus" rule where upon the 5th foul on a team in a quarter, the other team shoots free throws. They also have a "2 fouls in the last 2 minutes" rule where regardless of how many fouls a team has, the 2nd foul in the last 2 minutes results in free throws. The same could be instituted here. There should be a minimum (10? 15? 20?) battles that need to be fought during the last 2 or 3 days of the season. Too often people get on a win streak early in the season, post a number, and then just sit there with no risk of moving backwards.
I'm sure there would definitely need to be some work on the back end but tracking this data would probably be helpful in multiple ways, besides just making sure people aren't gaming the system.
It is a good point, something should be made to ensure participation. Moreover, I think that the brutal rating-drop that occurs when you are up on leader board level is a heavy deterrence from playing in the end. It was a long time ago when I realized that, even when I had the deck and the skill, I would not be able to stay on the leader board because of one poor game or whatever would knock off like 40 points. That made me stop trying. If we instead have a form of decay in points per hour or per day, instead of the major difference points lost vs points won getting over-sized it would encourage players to play more, and probably also more over the season. You could even say accumulate more decay if you don't play at all one full day or whatever. Of course I understand this is totally off-topic for this SPS Vote but I liked the discussion here!