They do what they feel is best for their team. They don't owe you or anyone else an explanation. If the Nats take care of business they don't have to concern themselves with expecting charity from other teams. Quit being a freaking nag about it.
But they are violating one of the unwritten rules by tanking against a team in a pennant race.
At least I'm pretty sure there's an unwritten rule on that. I'd look it up, but it is unwritten.
Then again, I just wrote, so how can it be unwritten?
I really should ask someone who is a Knight Templar of Unwritten Rules. Know anyone?
Earvin Santana? I bet it took some fancy footwork to come up with that.