Player rating for tournaments across all installments of Heroes.

Here. It's closer now. Let's consider someone who completed it in 10 days. They got 40 points, is that good or bad? If a player is new to tournaments and has a low rating, say 100, they'll get approximately 100 - 10 + 40 = 130. So, they still improved. Right?
But if they're a super player with a rating of 900, then 900 - 90 + 40 = 850. Those points don't matter to them. The decrease is insignificant; they might say they just played casually for a day to get it.

And with a reduction of 1/3:
First case: 2 * 100 / 3 + 40 = 67 + 40 = 107. They're still in the plus :(
Second case: 2 * 900 / 3 + 40 = 600 + 40 = 640. Now that's worth it :) They played well for free :)