It was reported this past fall that the Nationals requested their annual payment from MASN be increased from 29 MM a year to 100 MM a year. Supposedly, the powers that be at MASN countered with 37 MM. That set in motion MLB trying to broker a deal with Fox to purchase MASN with, again supposedly, the goal of splitting the markets from each other. This is not the first time or second or probably third time a group came forward to purchase MASN, but this is the first time that I am aware that MLB was involved.
Below is a graph devised from Wendy Thrum's work at FanGraphs as well as a couple things I have been told. I was unable to find anyone who could give a decent approximation of the Giants deal.
It is actually interesting to think that perhaps the Orioles depend on the Nationals to increase their own payroll by having to match whatever is allotted for the annual TV payout. It would not be surprising if the total value of this region is about 120-140 MM with more of the money leaning to the DC Market.