This is correct. He could have had two lights out starts and had a major impact. He also would have likely cancelled Det's start, so that would have been lost. So, who knows. He also could have had a bad start (a la Wainright) and then put the morale of the team in the toilet. It is simply impossible to know what would have happened. Saying that if he had not been shutdown we would have won is hogwash, because we don't know if it would have happened or if not shutting him down could have had the opposite impact where he faltered in remaining starts and we ended up losing out to the Braves and/or losing worse in the playoffs.
Again, the only argument is whether they should have opted to protect the player or roll the dice. It's a question of priorities.
Priorities and probabilities, in my opinion the probability of Stras making a positive impact on the Nats playoff performance was very high, the probability of 4-5 extra starts having a negative long term affect on his career was very low.