What Frankie is saying is the fight game isn't like a traditional business.
There is certain guarantees that go into it before the event even happens and most of it is based of gross because that is the only amount anyone knows going into the event.
Take a concert promoter for example(lots of data out there to support this and I happen to have knowledge on it) who brings band "x" to town. That band may offer a few different ways to pay them depending on there level of success. One might be a flat fee (50% up front and 50% before they go on stage). Another way, you pay band "x" a set amount(usually lower than the first example, it guaranteed even if 5 people only show up) and every ticket sold you pay the band an additional $10 or whatever amount is negotiated. These are two of the most common methods when dealing with what I'd call mid level bands that play 500 to 3000 seat places. Based on those stipulations the concert promoter and the band have to figure out if they can make money or not on that show. The later method the band is being paid per a ticket sold based on that gross amount of the ticket. Not net after the dust settles, that is the promoter's problem.
Remember Tito and Chuck are the attraction Golden Boy is paying for. They aren't business partners in the traditional business sense and share both the profits and loses.