I checked out some numbers:
Cleveland: 22,530 avg attendance, $81.6M opening day payroll, $21.54 avg ticket price
Pittsburgh: 18,918 avg attendance, $48.6M opening day payroll (according to MLB.com), $15.39 avg ticket price.
Cleveland projects to make $39.3M in ticket revenues, yielding a payroll/ticket revenue ratio of 2.1. Pittsburgh projects to make $23.6M in ticket revenues, also yielding a payroll/ticket revenue ratio of 2.1.
The big difference appears to be the gap between payroll and ticket revenue: Cleveland is $42.3M and Pittsburgh is $25.4M, a difference of $16.9M.
I suspect that the non-ticket revenues for Cleveland and Pittsburgh should be similar and that the economies of the two cities are similar as well, so I think a comparison to Cleveland is appropriate.
Bottom line is that the only way for the Pirates to increase payroll beyond $50M and not lose money is to have more attendance. The irony is that their recent actions may well have hurt attendance, making it less likely that money will be available for higher salaries in the future...at least until they start winning.
There may be some flaws in my admittedly quick back of the envelope calculations, but it's food for thought, anyway