Not following you. Please explain. How does not announcing the game times for the NLDS games in DC impact ratings?
Might impact national ratings - if game 3 turns out to be a big game for the Cards/Nats they might move it closer to prime time where they believe it might get more ratings than another game in the same spot.
Also the A's might be eliminated by Wednesday (and possibly the Giants too), so they want to make sure that there aren't unused time slots based on a game that does not need to be played.