Yeah, post monthly bonuses is some kind of bonus I've come to understand meant some kind of compensation to losers, that is, those who lost more during the month usually stand a better chance of getting a hire bonus amount than those who lost a few but won more.
So far the post monthly bonus can be called a fixed bonus which is determined based on VIP level so win/lose has no impact on the total bonus, the formula is completely different from the monthly bonus. I am on Platinum 1 and I lost about $600 this month normally the bonus for Platinum 1 is $15 For Bronze it's around $1 and Silver $2 well try comparing it with your VIP level, I'm sure you'll get the bonuses I mentioned. Post monthly or pre monthly are generally distributed for celebration like new inhouse games or something else so the bonus fixed based on VIP level.
It was fixed but it is no longer fixed since they have changed it few months back, now a user can get bigger amount than before (when it was fixed) especially if the user wager a lot or lose a lot.
The formula is now similar to monthly or weekly bonus if you ask me, but of course it is not 100% the same formula but similar because it is completely different than when it was fixed.