This response was little help to me. The MLB logo shows up in the default menu of the Apple TV device. That says to me that Apple and MLB are working together to offer the service, but there are no indications on the screen as to what is available in each jurisdiction.
In the end I found that I was able to buy the MLB broadcast (if that is the right word) through the menu on the Apple TV. The very poor display of the Apple TV network test left me no clearer as to whether or not I would have sufficient bandwidth. I decided to purchase one month of MLB to try it out and ended up paying a bit over $30 for the month rather than $24, and it came up as a RECURRING charge! The display of the game was reasonable (not great), and there were a few times it stalled, but generally it was all right.
I have also created a task in my Outlook to cancel the subscription before the 30 days expires.
If I decide that I want the season I'll try to find a way to buy the season through MLB at $99 rather than 12 times $30!