I think the story could be true (that the team is in the red at times). Keep in mind that cash flow and profits are two different things. They are not really losing money because the value of the franchise is increasing, but they could well be operating, at times, at a negative cash flow.
There has not been a capital call from ownership, or any additional investment of any kind, in the 22 years since Boston Basketball Partners bought the team and we don't anticipate there being one.
This is the key statement. If there have been any periods of negative cash flow, they were managed well enough so that none of the investors had to put in more capital (cash). I suspect they have a line of credit that they dip into from time to time to smooth things out so that the cash doesn't need to come out of the partner's pockets.
Profits (retained earnings) get taxed but there are many ways to manage this. I bet pretty much every year, the partners all get a dividend check so that the team or the business unit shows a break even or a loss. Or they figure out ways to reinvest the profits into the business.
So unless they have run up a bunch of debt, they can't be losing money overall if the partners are not putting more money into the business. If they were in fact losing money overall from an operational standpoint, either the partners would have to be making up the difference with new cash or they would have to be running up new debt. They have stated that the former has not happened, it is possible that the latter is true though.