Player rating for tournaments across all installments of Heroes.

You haven't even mentioned the differences between leaders in equally-matched tournaments on 2.5.

The tournaments aren't equally matched. Player C beat twice as many players, so his rating is higher. But the ratings themselves are so insignificant that you can safely say that the players wasted their time.

A hundred points is a pretty decent result in 5 days.

And what makes you think that's a decent result? Maybe an average player can complete the map in a day. And in the tournament, only super-skilled players participated.