Player rating for tournaments across all installments of Heroes.

I disagree. Everything depends on the current rating.
The bonus for victory will be equal for all players, but the 10% decay for each will be a different burden... And the pressure on the leader will be significantly higher than on an underdog. I think there's no need to provide figures.

Where is this "equal bonus" — come on, give me some numbers then :) The leader gets 100, and the rest get it depending on how many days they took to finish and how close they got to the leader. And the leader doesn't care about 10%. He takes 100, and in the next tournament, he takes 100 again. Total: 90+100=190. And now he can take a long break thanks to you :) Because from 190, he will drop much slower than from 100. And with 1000, you'll be waiting forever. Vasya Pupkin is still going to crush you on the same map :)