Well, indeed we and other would not be talking about those bonuses of Stakes did not keep this aura of mystery on how big our next bonus is going to be, perhaps they have noticed how bonuses are not such a relevant topic on other gambling communities or casinos and their marketing and PR department thought it was a good idea for them not to make public the way they compute bonuses realizing they were going to get some engagement plus from gamblers.
After all, gambling is unpredictable and if bonuses are unpredictable, they become just another tool or low paced "game" for the casino to keep us engaged.