The Nats and Reds are the only two teams with 90 wins so far. They have one very important thing in common.
Nats Starters :
Gio - 30 starts, ZNN - 30 starts, EJax - 28 starts, Strasburg - 28 starts, Detwiler - 24 starts (removed from rotation because of Wang love, not injury or performance)
Reds Starters :
Cueto - 30, Latos - 30, Bailey - 30, Arroyo - 29, Leake - 29
It's not a coincidence. As much as we may focus on offensive injuries, like the one to Danny, you can work around most of those. First of all, you probably have a decent bat that you can fill in for the guy. Maybe not great but someone where the drop-off isn't astronomical. You are going to try to use that guy, who's actually probably not even your 9th best hitter, but more like your 6th or 7th and ride it out in the field. It is possible. First and corner OF spots are playable by nearly anyone. Usually another OF can pretend to be a CF for a while (so you can put a hitter in the corner), or a bat can hope to hide at 3rd. Even if your shortstop goes down, you may be able to shift a 2B to SS and put a "should be a corner IF" at second (it's the Danny Murphy story!). Only catcher is the place where you can't possibly cover the loss of a bat if you so wish, and really the number of elite bats at catcher don't make me go over to the 2nd counting hand. Plus that injury is still only one bat. If he has to miss a month well maybe his replacement happens to have a hot streak for a couple weeks and the other time the rest of the team starts hitting. You can get lucky and have it go by unnoticed.
Lose a #1 or #2 pitcher though and you have a hell of a time recovering. You are immediately getting your #6th best starter, no way around it, and the drop-off is going to be severe. It's like going from Albert Pujols to James Loney. The good news is it's only every 5th day. The bad news is that 6th guy is unlikely to go on a hot streak for a month. He may give you a good start or two, but miss any significant time and you will notice this guy is much worse than the original. That's with one major injury. What if you have 2 starters miss significant time? That happens all the time. 3? Not uncommon. Suddenly that rotation is at best hanging on and at worse pushing your team right out of contention.
I bring this up because last night you saw what an injury could have meant. John Lannan and/or Chein-Ming Wang. I think John is a fine back of the rotation starter, but the Nats don't really have a back of the rotation. They have an extended top, followed by the middle. John is a step down from what they are putting out there. A major injury to one pitcher and the Nats are losing a few more games, putting them in a dogfight with the Braves. A major injury to two and they are probably behind the Braves and maybe fighting for a playoff spot (depends on how bad Wang and whoever else really is). Probably in the lead for one, but still fighting.
This isn't meant to be a comment on Strasburg. We don't know if the shutdown will help future injuries, so we can't say the shutdown is right. We also don't know the make-up of next year's squad and we can't say that the Nats can't compete for the title if they do get more normal luck and see a guy or two go down, so we can't say the shutdown is wrong. This year though, 2012, the Nats are able to be where they are, on cruise control toward an NL East title, because of some nice injury luck with the pitching staff.